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Etherchannels

Etherchannel Concept and configuration

EtherChannel is a port link aggregation technology or port-channel architecture used primarily on Cisco switches. It allows grouping of several physical Ethernet links to create one logical Ethernet link for the purpose of providing fault-tolerance and high-speed links between switches, routers and servers. An EtherChannel can be created from between two and eight active Fast, Gigabit or 10-Gigabit Ethernet ports, with an additional one to eight inactive (failover) ports which become active as the other active ports fail. EtherChannel is primarily used in the backbone network, but can also be used to connect end user machines.

Using an EtherChannel has many advantages

Larger bandwidth. By using the maximum of 8 active ports, a total bandwidth is increased 8 fold comparing to a single port.
Scalable. Because EtherChannel takes advantage of existing wiring it makes it very scalable. It can be used at all levels of the network to create higher bandwidth links as the traffic needs of the network increase. All Cisco switches have the ability to support EtherChannel.
transparent to network applications. When an EtherChannel is configured, all adapters that are part of the channel share the same Layer 2 (MAC) address. This makes the EtherChannel transparent to network applications and users because they only see the one logical connection; they have no knowledge of the individual links.
Fault-tolerance. Should a link fail, the EtherChannel technology will automatically redistribute traffic across the remaining links. This automatic recovery takes less than one second and is transparent to network applications and the end user. This makes it very resilient and desirable for mission-critical applications.

Spanning tree protocol (STP) can be used with an EtherChannel. STP treats all the links as a single one and BPDUs are only sent down one of the links.

EtherChannels can be also configured as VLAN trunks. If any single link of an EtherChannel is configured as a VLAN trunk, the entire EtherChannel will act as a VLAN trunk.

EtherChannel is made up of the following key elements:

Ethernet links — EtherChannel works over links defined by the IEEE 802.3 standard, including all sub-standards. All links in a single EtherChannel must be the same speed.
Compatible hardware — the entire line of Cisco Catalyst switches as well as Cisco IOS software-based routers support EtherChannel. Multiple EtherChannels per device are supported (Catalyst 6500 and 6000 switches support a maximum of 64 EtherChannels).
Configuration — an EtherChannel must be configured using the Cisco IOS on switches and router, and using specific drivers when connecting a server. There are two main ways an EtherChannel can be set up. The first is by manually issuing a command on each port of the device that is part of the EtherChannel. This must be done for the corresponding ports on both sides of the EtherChannel. The second way is using Cisco Port Aggregation Protocol (PAgP) for the automated aggregation of Ethernet ports.

EtherChannel vs. 802.3ad

EtherChannel and IEEE 802.3ad standards are very similar and accomplish the same goal. There are a few differences between the two, other than the fact that EtherChannel is Cisco proprietary and 802.3ad is an open standard, listed below:

Both technologies are capable of automatically configuring this logical link. EtherChannel supports both LACP and Cisco's PAgP, whereas 802.3ad uses LACP.

LACP allows for up to 8 active and 8 standby links, whereas PAgP only allows for 8 active links.

Cisco Lab

[ICND1 and ICND2 break down]

RSTP and PVST

Rapid spanning tree protocol (RSTP)

Rapid Spanning Tree Protocol (RSTP), which was designed to take over the duties of STP was standardized in IEEE 802.1w and 802.1D. Compare to STP, RSTP has shorter converge time both on startup and failure recovery.

(R)STP attempts to avoid this endless loop problem by removing the redundant path. Both RTP and RSTP need to elect a root bridge (or switch) based on priority and bridge ID.

These priorities and bridge IDs are relayed through the exchange of Bridge Protocol Data Units (BPDUs), which are sent by RSTP every “hello” interval—by default, every two seconds. The bridge that has the superior priority or bridge ID is elected the root bridge.

A big difference between the original STP and RSTP is in how they converge. With the original STP, all of the switches must wait as the interfaces go through blocking (at startup), listening, learning port states (total 50 seconds) before transition to forwarding state. With RSTP, a proposal and agreement (P/A) process is put in place, which is automatically used as soon as an interface comes up. This P/A process drastically shortens the time needed for an interface to move into a forwarding state. However, this process only happens on what RSTP calls point-to-point (p2p) links.

Cisco switches use the duplex setting of an interface to determine the link type. Interfaces with a full-duplex setting follow the P/A process; interfaces with a half-duplex setting go through the slower STP convergence process (30 seconds total) before converging. An exception to this rule is root ports, which are automatically pushed into a forwarding state when a switch is brought up. In RSTP, these half-duplex links are referred to as shared (Shr) links. RSTP also defines a third type of link, edge links; these ports operate like older Cisco PortFast ports and are automatically put into a forwarding state.

RSTP has a 4 types of ports. The alternative and backup ports does not exit for for STP. These states are a method of indicating preferred secondary paths. The alternative port state indicates that an interface will be the next potential root port if the current root port fails. The backup port state indicates that an interface will be the next potential designated port; this only happens when a switch has multiple links into the same Ethernet segment.

root port: a forwarding port that forwards frame from Non-root bridge to Root bridge.
designated port: the frame exiting port for every LAN segment.
alternate port: as it name implies, is an alternate path to the root bridge which does not use the root port.
backup port: a redundant path to a segment where another bridge port already connects.

The port states are also referenced differently in RSTP. STP has five port states: disabled, blocking, listening, learning, and forwarding. RSTP combines those states into a total of three: discarding (disabled, blocking, listening), learning, and forwarding.

Discarding – wherein a port discards information received on the interface, discards frames switched from another interface for forwarding, does not learn MAC addresses, and listens for BPDUs.
Learning – a situation where the switch creates a switching table that will map MAC addresses to a port number. It also happens when a port discards frames received on the interface, discards frames switched from another interface for forwarding, learns MAC addresses, and listens for BPDUs.
Forwarding – wherein a port receives and forwards the frames received on the interface, forwards frames switched from another interface, learns MAC addresses, and listens for BPDUs.

PVST -- Cisco’s RSTP Implementation

Cisco’s default implementation of STP differs from the standard. Instead of using a single STP instance that works over all of the network, including over all configured VLANs, Cisco implements an STP instance for each specific VLAN, which is referred to as Per-VLAN Spanning Tree (PVST).

It is based on the 802.1D standard and uses Cisco proprietary ISL trunking protocol. It prevents creating a loop by forwarding some VLANs on another trunk. It is the default spanning-tree mode used on all Ethernet port-based VLANs.

PVST is succeeding by Cisco proprietary extensions like BackboneFast, UplinkFast, and PortFast.

Cisco Lab

Here is an video demonstrating how to configure RSTP on sisco switches.

[ICND1 and ICND2 break down]

“Router on a Stick”

So far we have been exposed to "Router on a Stick" configuration twice. One is the second video in CCENT Virtual LANs, another time is in CCNA VLANs and Trunking.

Router-on-a-stick is a term frequently used to describe a setup up that consists of a router and switch connected using one Ethernet link configured as an 802.1q trunk link.

router on a stick

As the picture shows, a router is used to allow inter-VLAN communication. There is only a single cable connecting the switch and the router, so the router is sitting on a stick (instead of 2 sticks).

the switch config involves:

configuring the VLANs
configure a port as trunk mode in order to connect to router

Switch(config)#vlan 10
Switch(config-vlan)#exit
Switch(config)#vlan 20
Switch(config-vlan)#exit
Switch(config)#vlan 30
Switch(config-vlan)#exit
Switch(config)#interface FastEthernet0/4
Switch(config-if)#switchport trunk encapsulation dot1q
Switch(config-if)#switchport mode trunk

the router config include:

select a physical port as the port connecting to switch.
configure a sub interface for each VLAN on the switch.

Router(config)#interface gigabiteEthernet0/0
Router(config-if)#no ip address
Router(config-if)#interface gigabiteEthernet0/0.10
Router(config-subif)#encapsulation dot1Q 10
Router(config-subif)#ip add 192.168.5.1 255.255.255.0
Router(config-subif)#interface gigabiteEthernet0/0.20
Router(config-subif)#encapsulation dot1Q 20
Router(config-subif)#ip add 192.168.10.1 255.255.255.0
Router(config-subif)#interface gigabiteEthernet0/0.30
Router(config-subif)#encapsulation dot1Q 30
Router(config-subif)#ip add 192.168.15.1 255.255.255.0

[ICND1 and ICND2 break down]

VTP

The VLAN trunking protocol (VTP) is a Cisco-proprietary protocol that provides a way to manage Cisco switches as a single group for VLAN configuration. It ease the burden of configuring individual VLANs on multiple switches. VTP defines a VTP management domain where Cisco switches in the domain have VTP enabled. With VTP, you can create a new VLAN on one switch, and have VTP spread the information and configure the same VLAN on all other switches in the same domain automatically.

Each switch in a VTP management domain must be configured in one of four possible VTP modes:

Server mode: A switch configured in server mode can be used to add, delete, and change VLANs within the VTP management domain. It is the default VTP mode. There must be at least one switch with server mode per VTP management domain. Changes in the server are passed to all other switches in the VTP management domain.
Client mode: A switch configured in client mode is the recipient of any changes within the VTP management domain, such as the addition, deletion, and modification of VLANs by a server mode switch. A switch in VTP client mode cannot make any change to VLAN information.
Transparent mode: A witch configured in transparent mode passes VTP updates received by switches in server mode to other switches in the VTP management domain, but does not process the contents of these messages. When individual VLANs are added, deleted, or changed on a switch running in transparent mode, the changes are local to that particular switch only, and are not passed to other switches within the VTP management domain.
Off: The option disable VTP completely on a switch, it is only available after COS version 7.1.1.

[ICND1 and ICND2 break down]

Access and Trunk Port Comparison

In last section VLANs and trunking, we have talked about access link and trunk link, here is a recap:

trunk link - frames entering trunk link will be sent with VLAN tag.
access link - frames entering access link will be sent untagged.

The switch ports of a trunk link are trunk ports, the switch ports of the access link are access ports.

A frame received on an access port (i.e., sent from a host) is not VLAN tagged. It is the switch that tags the frame (with the VLAN number that is assigned to the receiving access port). If it needs to send that frame out on the trunk port. If the frame is destined for another access port, the frame is not tagged.

If a frame comes in on a trunk port it should already be tagged with a VLAN number (unless it is in the native VLAN which is not tagged). The switch then strips the VLAN tag and sends it out on the appropriate access port (or ports if broadcast) to its destination.

Depends on the model, the switch port is by default dynamic auto.
we can change the switch port mode to trunk to allows all vlans(pretagged) traffic to flow to and from it. It is most common to use 802.1q as vlan tagging method.

int fa0/0

switchport mode trunk

switchport trunk encapsulation dot1q

We can also change the switch port mode to access then assign a VLAN ID to this port.

int f0/1

switchport mode access

switchport access vlan 10

Here is an cisco lab configuring both access port and trunk port.

[ICND1 and ICND2 break down]

VLANs and Trunking

LAN vs VLAN

Ethernet LANs are broadcast domains where information transmitted by any network device in the domain is received by all devices attached to the LAN via the shared transmission medium. In a LAN with many devices, if only hubs are used in the network, a single large broadcast domain is created and the frequent broadcast messages can easily consumes all the bandwidth. Broadcasts are stopped only at the router, which is the edge of the broadcast domain, before traffic is sent across the WAN.

If we replace the hubs with switches, we can create VLANs within the existing large physical broadcast domain, in order to segment and isolate network traffic, reduce unnecessary broadcast traffic.

A virtual LAN, or VLAN, is a group of computers, network printers, network servers, and other network devices that behave as if they were connected to a single network. Hosts belong to a VLAN share the same VLAN ID, and hosts with the same VLAN ID behave as if they are on the same physical network. In its basic form, a VLAN is a broadcast domain. The difference between a physical broadcast domain and virtual broadcast domain defined by a VLAN is that a broadcast domain is seen as a distinct physical entity with a router on its boundary. VLANs are similar to broadcast domains because their boundaries are also defined by a router. However, a VLAN is a logical topology, which is independent of the physical topology -- it can contains a group of devices on either the same or different physical LAN segments, those ones physically wired with cables.

Another advantage of VLAN is that users can be grouped according to their logical communication requirement instead of physical location. Your sales team might spread across different floors, different building, or even different cities, as long as their computers belong to the same VLAN, they can communicate to each other as if they are in the same physical LAN segment.

VLAN membership

There are three types of VLANs depending on how they decide VLAN membership.

Port-based VLAN: computers are assigned to a VLAN based on the switch port to which the computer is connected. When the same computer is connected to a different switch port, its VLAN membership might change if the other switch port are assigned to a different VLAN.
MAC-based VLAN: a computer is assigned to a VLAN according to its MAC address. The advantage of MAC-based VLAN is PCs can move around all the time and still belongs to the same VLAN without extra configuration. However, since PC's MAC address is tied to a particular VLAN, changing its VLAN membership is harder comparing to port-based VLAN. Network administrator needs to configure it at switch side or the switch side has special feature to support multiple VLAN membership.
IP-based VLAN: a computer is assigned to a VLAN based on network layer address, such as IP address. IP-based VLAN can keep the PC's IP address when they moves around. Note switches are layer 2 devices. Even though layer 3 IP address is used to differentiate VLAN members, the device is assigned to a layer 2 broadcast domain. The switch still forwards frames instead of packets. Due to additional switch processing, IP-based VLAN tend to have worst performance among the 3 types of VLANs.

VLAN to VLAN communication

When a host in one broadcast domain wants to communicate with another host in a different broadcast domain, the packets have to travel cross the domain border via a router. Since VLANs are basically broadcast domains, inter-VLAN communications also have to involve a router.

The routing function can either be provided by a router a layer 3 switch.

In the case of a router, the message delivery process is:

a VLAN A PC1 connected to switch port 1 sends traffic to VLAN B PC2.
The traffic leaving the host in VLAN A reaches the switch through the switch port 1.
Switch saw the destination belongs to a different broadcast domain, so it pass the traffic to the router via switch port 2.
router checks its routing table, passes the traffic back to the switch port 3.
switch gives the traffic to the host PC2 in VLAN B via port 4.

A layer 3 switch is essentially a layer 2 switch that can also act as a router. If a switch is capable of being configured to route traffic between VLANs defined within the switch, the inter-VLAN traffic doesn't have to leave the switch for routing decision. Even though layer 3 switch need additional hardware and software feature to support routing, it saves a physical router device as well as reduce unnecessary routing traffic, therefore they are very popular in corporate network.

VLAN trunks

We can interconnecting switches to create bigger VLANs, these interconnections are called trunk links. Trunk links generally are faster than the VLANs they are connecting, because these links sometimes need to carry the traffic of more than one VLANs.

A simple case is extending a VLAN (say VLAN 10) to another switch. In order to do that, we configure VLAN 10 on the second switch, then connect a VLAN 10 port on the first switch to a VLAN 10 port on the second switch with a cable. By default, these connected ports act as a trunk link between these two switches. However, since these ports pass traffic only for the VLAN 10, this type of link, in which traffic for only a single VLAN is passed, is referred to as an access link, as opposed to a trunk link, which carries traffic for multiple VLANs.

When multiple VLANs need to pass traffic between switches, we need to assign an access link for each VLAN, which occupies lots of switch ports. These VLANs can share a single trunk link instead of having a dedicated access link for each one of them. Now VLANs traffic are mixed in the shared trunk link, therefore, at the receiving switch, in order to identify the destination VLAN's traffic, VLAN tagging is used.

Inter-Switch Link (ISL) and 802.1q are two of the tagging technologies. ISL is a Cisco proprietary VLAN tagging method; 802.1q is an open standard both cisco and non-cisco switches support.

ISL and 802.1q are similar in operation. ISL for example, tags a frame as it leaves a switch, the tagging adds additional information to the frame about which VLAN the frame belongs to. When the tagged frame reaches the port at the receiving switch, the switch looks at the ISL header, determines which VLAN the frame belongs to, then removes the ISL tag, then forwards the frame into the VLAN specified in the VLAN tagging.

After VLAN tagging has been configured on the ports associated with the link connecting switches, the link is known as a trunk link.

Cisco lab

We have talked enough about VLANs and VLAN trunks, lets put all these concepts together by configure VLANs involving a few PCs, 2 cisco swithces and a router. The following video demonstrates how to configure VLANs and VLAN trunks, it also shows how to configure a router to route traffic between VLANs (router on a stick).

[ICND1 and ICND2 break down]

Root Bridges, Root Ports, and Designated Ports

Root Bridges

STP establishes a tree with root and branches. (In this section, we use switches and bridges interchangeably, knowing that they performs the same function -- a bridge with more than 2 ports can also be called switch.) The primary decision-making switch in an STP environment is called the root bridge. The frames flows out from the root bridge to form a logical branched network. All switches in a LAN participating in STP branch from the root switch/bridge port.

The first problem the STP must solve is to decide where the spanning tree begins by electing a root bridge or switch port. The root bridge is used to build a reference point in the network, with which all paths from all bridges must be traceable back to the root bridge. All paths not needed to trace back to the root bridge are placed in backup mode. Each switch in the network exchange information about the network topology with neighbor switches in the same network through a data units called bridge protocol data units, or BPDUs.

Bridge Protocol Data Units (BPDUs)

BPDUs are data messages exchanged between the switches and bridges within an extended LAN using the STP. A BPDU frame contains information on originating switch's port, MAC address, switch port priorities and cost to reach root bridge and ensure that the data ends up where it was intended to go.

SPT assign each switch in the extended LAN a unique bridge ID. The bridge ID contains bridge priority followed by MAC address, which is the 48 byte hardware address of the NIC. By default, all STP switches have a bridge priority value of 32,768. After the exchange of BPDUs, the switch with the lowest priority value becomes the root bridge.

Root Ports

SPT have to answer the question of among many possible paths from a switch to root bridge, which one is the the lowest cost path. The root port represent a switch's lowest cost path to the root bridge.

The cost of a switch is based on the number of network segments a frame has to traversal in order to reach its destination. Besides switch cost, each individual ports on the switch also have a cost called port cost. The port cost is determined by the network bandwidth -- the faster the port, the lower its cost. For example, the default IEEE cost for Fast Ethernet (100Mbps) is 10 and Ethernet (10Mbps) is 100. A switch uses the port cost to determine the root port for each switch in the network. All nonroot bridges have one root port that is used as the link over which data traffic is forwarded across the network; the nonroot ports are either standby or disabled.

Designated Ports

On a spanning-tree network, each network segment has one port identified as the designated port. The designated port is the port that is the single interface to forward traffic to the root bridge. Since there could be multiple bridges connected to a segment, on each segment, STP need to select one of the connected bridge ports as the designated port. This is always the switch port on the segment with the lowest port cost. When two ports has the same port cost, MAC addresses are used to determine the designated port, port with lower MAC address is selected as designated port. Once STP elected the designated port for a network segment, the designated port is put to forwarding mode, while the rest of the ports connected to network segment are put to blocking mode. As a result, all traffic from this network segment will exit the segment via the designated port.

As you can see from above, root port and designated port are elected based on the same criteria -- the lowest port cost, which is decided by the network link connected to it. Therefore once you find a root port, on the other side of the network link, you will find a designated port.

[ICND1 and ICND2 break down]

Module 2 Exam

1. Which layer of the OSI model provides network services to processes in electronic mail and file transfer programs?
• data link
• transport
• network
• application

2. Which of the following are data link layer encapsulation details? (Choose two.)
• A header and trailer are added.
• Data is converted into packets.
• Packets are packaged into frames.
• Frames are divided into segments.
• Packets are changed into bits for Internet travel.

3. Which three features apply to LAN connections? (Choose three.)
• operate using serial interfaces
• make network connection using a hub
• limited to operation over small geographic areas
• provide part-time connectivity to remote services
• typically operate under local administrative control
• provide lower bandwidth services compared to WANs

4. Which layer of the OSI model provides connectivity and path selection between two end systems where routing occurs?
• physical layer
• data link layer
• network layer
• transport layer

5. Which term describes the process of adding headers to data as it moves down OSI layers?
• division
• encoding
• separation
• segmentation
• encapsulation

6. Refer to the following list. Choose the correct order of data encapsulation when a device sends information.
1. segments
2. bits
3. packets
4. data
5. frames
• 1 – 3 – 5 – 4 – 2
• 2 – 1 – 3 – 5 – 4
• 2 – 4 – 3 – 5 – 1
• 4 – 3 – 1 – 2 – 5
• 4 – 1 – 3 – 5 – 2
• 3 – 5 – 1 – 2 – 4

7. The central hub has malfunctioned in the network. As a result, the entire network is down. Which type of physical network topology is implemented?
• bus
• star
• ring
• mesh

8. Which of the following are factors that determine throughput? (Choose two.)
• types of passwords used on servers
• type of Layer 3 protocol used
• network topology
• width of the network cable
• number of users on the network

9. Which best describes the function of the physical layer?
• Defines the electrical and functional specifications for the link between end systems.
• Provides reliable transit of data across a physical link.
• Provides connectivity and path selection between two end systems.
• Concerned with physical addressing, network topology and media access.

10. Which of the following are ways that bandwidth is commonly measured? (Choose three.)
• GHzps
• kbps
• Mbps
• Nbps
• MHzps
• Gbps

11. Which of the following are layers of the TCP/IP model? (Choose three.)
• Application
• Physical
• Internet
• Network Access
• Presentation

12. What is the term used to describe the transport layer protocol data unit?
• bits
• packets
• segments
• frames
• data streams

13. What makes it easier for different networking vendors to design software and hardware that will interoperate?
• OSI model
• proprietary designs
• IP addressing scheme
• standard logical topologies
• standard physical topologies

14.

5535

Refer to the exhibit. Which column shows the correct sequence of OSI model layers?
• A
• B
• C
• D

15. What is one advantage of defining network communication by the seven layers of the OSI model?
• It increases the bandwidth of a network.
• It makes networking easier to learn and understand.
• It eliminates many protocol restrictions.
• It increases the throughput of a network.
• It reduces the need for testing network connectivity.

16. Which two features apply to WAN connections? (Choose two.)
• operate using serial interfaces
• make network connection using a hub
• limited to operation over small geographic areas
• typically operate under local administrative control
• provide lower bandwidth services compared to LANs

17. A switch has failed in the network. As a result, only one segment of the network is down. Which type of physical network topology is implemented?
• bus
• ring
• star
• extended star

18.

8837

Refer to the exhibit. Identify the devices labeled A, B, C, and D in the network physical documentation.
• A=bridge, B=switch, C=router, D=hub
• A=bridge, B=hub, C=router, D=switch
• A=bridge, B=router, C=hub, D=switch
• A=hub, B=bridge, C=router, D=switch

Answers and Explains

Exam 5 -- 18 Question Set

Exam Source

Study Guides:

Lesson 1
Introduction to Networking and the Networking Models

Cover the theory needed for the exam, to accelerate Cisco networking career and for troubleshooting experience

* What is A Network?
* The OSI Model
* The Data Transmission Process
* The TCP/IP Model
* TCP And UDP
* Ports, Sockets and Port Numbers
* Network Topology

1. Which layer of the OSI model provides network services to processes in electronic mail and file transfer programs?
• data link
• transport
• network
• application

2. Which of the following are data link layer encapsulation details? (Choose two.)
• A header and trailer are added.
• Data is converted into packets.
• Packets are packaged into frames.
• Frames are divided into segments.
• Packets are changed into bits for Internet travel.

3. Which three features apply to LAN connections? (Choose three.)
• operate using serial interfaces
• make network connection using a hub
• limited to operation over small geographic areas
• provide part-time connectivity to remote services
• typically operate under local administrative control
• provide lower bandwidth services compared to WANs

4. Which layer of the OSI model provides connectivity and path selection between two end systems where routing occurs?
• physical layer
• data link layer
• network layer
• transport layer

5. Which term describes the process of adding headers to data as it moves down OSI layers?
• division
• encoding
• separation
• segmentation
• encapsulation

6. Refer to the following list. Choose the correct order of data encapsulation when a device sends information.
1. segments
2. bits
3. packets
4. data
5. frames
• 1 – 3 – 5 – 4 – 2
• 2 – 1 – 3 – 5 – 4
• 2 – 4 – 3 – 5 – 1
• 4 – 3 – 1 – 2 – 5
• 4 – 1 – 3 – 5 – 2
• 3 – 5 – 1 – 2 – 4

7. The central hub has malfunctioned in the network. As a result, the entire network is down. Which type of physical network topology is implemented?
• bus
• star
• ring
• mesh

8. Which of the following are factors that determine throughput? (Choose two.)
• types of passwords used on servers
• type of Layer 3 protocol used
• network topology
• width of the network cable
• number of users on the network

9. Which best describes the function of the physical layer?
• Defines the electrical and functional specifications for the link between end systems.
• Provides reliable transit of data across a physical link.
• Provides connectivity and path selection between two end systems.
• Concerned with physical addressing, network topology and media access.

10. Which of the following are ways that bandwidth is commonly measured? (Choose three.)
• GHzps
• kbps
• Mbps
• Nbps
• MHzps
• Gbps

11. Which of the following are layers of the TCP/IP model? (Choose three.)
• Application
• Physical
• Internet
• Network Access
• Presentation

12. What is the term used to describe the transport layer protocol data unit?
• bits
• packets
• segments
• frames
• data streams

13. What makes it easier for different networking vendors to design software and hardware that will interoperate?
• OSI model
• proprietary designs
• IP addressing scheme
• standard logical topologies
• standard physical topologies

14.
5535

Modual 1 Exam

1. Several computers in the company require new NICs. A technician has located a good price on the Internet for the purchase of these NICs. Before these NICs are purchased and installed, what details must be verified? (Choose three.)
• the MAC address on
• the NICthe size of the RAM on the NIC
• the bandwidth supported by the NIC
• the type of media supported by the NIC
• the type of network architecture supported by the NIC

2. What is the hexadecimal equivalent for the binary number 00100101?
• 15
• 20
• 25
• 30
• 37
• 40

3. Which phrases describe a byte? (Choose two.)
• a single binary digit
• +5 volts of electricity
• the value range 0 to 127
• a grouping of eight binary digits
• a single addressable data storage location

4. Which specialized equipment is used to make a physical connection from a PC to a network?
• router
• RAM
• CD ROM
• network interface card

5. What is the binary equivalent for the decimal number 248?
• 11100000
• 11110000
• 11110100
• 11111000

6. Convert the binary number 01011011 into its hexadecimal equivalent.
Select the correct answer from the list below.
• 5A
• 5b
• 5c
• 5d
• 6b
• 7a

7. What is the binary equivalent for decimal number 149?
• 10010111
• 10010101
• 10011001
• 10010111
• 10101011
• 10101101

8. In an 8 bit binary number, what is the total number of combinations of the eight bits?
• 128
• 254
• 255
• 256
• 512
• 1024

9. Which device connects a computer with a telephone line by providing modulation and demodulation of incoming and outgoing data?
• NIC
• CSU/DSU
• router
• modem
• telco switch

10. What is the binary equivalent for the decimal number 162?
• 10101010
• 10100010
• 10100100
• 10101101
• 10110000
• 10101100

11. Which of the following are popular web browsers? (Choose two.)
• Acrobat
• Internet Explorer
• Macromedia Flash
• Netscape Navigator
• Quicktime
• World Wide Web

12. Convert the Base 10 number 116 into its eight bit binary equivalent. Choose the correct answer from the following list:
• 01111010
• 01110010
• 01110100
• 01110110
• 01110111
• 01010110

13. What is the hexadecimal equivalent for the binary number 10001110?
• 22
• 67
• 142
• AE
• 8E

14. Represented as a decimal number, what is the result of the logical ANDing of binary numbers 00100011 and 11111100?
• 3
• 32
• 35
• 220
• 255

15. Convert the decimal number 231 into its binary equivalent. Select the correct answer from the list below.
• 11110010
• 11011011
• 11110110
• 11100111
• 11100101
• 11101110

16. What are three conditions that would require a network administrator to install a new NIC? (Choose three.)
• whenever a NIC is damaged
• when there is a need to provide a secondary or backup NIC
• when there is a change from copper media to wireless
• whenever operating system security patches are applied
• whenever the PC has been moved to a different location

Answer and Explains

Exam 4 -- 16 Question Set

Exam Source

Study Guides:

* Decimal > Binary, Binary > Decimal

* Ethernet Addressing

1. Several computers in the company require new NICs. A technician has located a good price on the Internet for the purchase of these NICs. Before these NICs are purchased and installed, what details must be verified? (Choose three.)
• the MAC address on
• the NICthe size of the RAM on the NIC
• the bandwidth supported by the NIC
• the type of media supported by the NIC
• the type of network architecture supported by the NIC

2. What is the hexadecimal equivalent for the binary number 00100101?
• 15
• 20
• 25
• 30
• 37
• 40

3. Which phrases describe a byte? (Choose two.)
• a single binary digit
• +5 volts of electricity
• the value range 0 to 127
• a grouping of eight binary digits
• a single addressable data storage location

4. Which specialized equipment is used to make a physical connection from a PC to a network?
• router
• RAM
• CD ROM
• network interface card

5. What is the binary equivalent for the decimal number 248?
• 11100000
• 11110000
• 11110100
• 11111000

6. Convert the binary number 01011011 into its hexadecimal equivalent.
Select the correct answer from the list below.
• 5A
• 5b
• 5c
• 5d
• 6b
• 7a

7. What is the binary equivalent for decimal number 149?
• 10010111
• 10010101
• 10011001
• 10010111
• 10101011
• 10101101

8. In an 8 bit binary number, what is the total number of combinations of the eight bits?
• 128
• 254
• 255
• 256
• 512
• 1024

9. Which device connects a computer with a telephone line by providing modulation and demodulation of incoming and outgoing data?
• NIC
• CSU/DSU
• router
• modem
• telco switch

10. What is the binary equivalent for the decimal number 162?
• 10101010
• 10100010
• 10100100
• 10101101
• 10110000
• 10101100

11. Which of the following are popular web browsers? (Choose two.)
• Acrobat
• Internet Explorer
• Macromedia Flash
• Netscape Navigator
• Quicktime
• World Wide Web

12. Convert the Base 10 number 116 into its eight bit binary equivalent. Choose the correct answer from the following list:
• 01111010
• 01110010
• 01110100
• 01110110
• 01110111
• 01010110

13. What is the hexadecimal equivalent for the binary number 10001110?
• 22
• 67
• 142
• AE
• 8E

14. Represented as a decimal number, what is the result of the logical ANDing of binary numbers 00100011 and 11111100?
• 3
• 32
• 35
• 220
• 255

15. Convert the decimal number 231 into its binary equivalent. Select the correct answer from the list below.
• 11110010
• 11011011
• 11110110
• 11100111
• 11100101
• 11101110

16. What are three conditions that would require a network administrator to install a new NIC? (Choose three.)
• whenever a NIC is damaged
• when there is a need to provide a secondary or backup NIC
• when there is a change from copper media to wireless
• whenever operating system security patches are applied
• whenever the PC has been moved to a different location

CCENT Final Exam 2 - 50 question set

Exam Source

Question 1: (QID=25141)

Which DHCP message is sent as a broadcast on the network?

1. DHCP Discover

2. DHCP Offer

3. DHCP Request

4. DHCP Acknowledgement

---------------------------------------------

Correct answer(s): 1

Explanation: The DHCP Discover message is sent as a broadcast on the network.

[Implement an IP addressing scheme and IP services to meet network requirements for a small branch office]

--------------------------------------------------------------------------------

Question 2: (QID=2352)

Given the following IP Address 172.45.34.1/24. What is the network and host portion?

1. Network 172.45.34 Host 1

2. Network 172 Host 45.34.1

3. Network 172.45 Host 34.1

4. This is an invalid IP Address

---------------------------------------------

Correct answer(s): 1

Explanation: 172.45.34.1/24 is the same as 172.45.34.1 255.255.255.0. So we can see from the subnet mask that the first 3 octets belong to the network portion of the IP Address and the 4th octet is the host portion.

[Implement an IP addressing scheme and IP services to meet network requirements for a small branch office]

--------------------------------------------------------------------------------

Question 3: (QID=25120)

You want to use RIPv2 as your routing protocol. Which commands will enable RIPv2 on your router?

A

router#configure terminal

router (config)#router rip version2

router(config-router)#network 10.0.0.0

router(config-router)#network 172.16.0.0

router(config-router)#^Z

B

router#router rip

router(config-router)#network 10.0.0.0

router(config-router)#network 172.16.0.0

router(config-router)#^Z

C

router#configure terminal

router(config)#router rip v2

router(config-router)#network 10.0.0.0

router(config-router)#network 172.16.0.0

router(config-router)#^Z

D

router#configure terminal

router(config)#router rip

router(config-router)#version 2

router(config-router)#network 10.0.0.0

router(config-router)#network 172.16.0.0

router(config-router)#^Z

1. A

2. B

3. C

4. D

---------------------------------------------

Correct answer(s): 4

Explanation: Only three steps are necessary to configure RIPv2:

Enable RIP with the command router rip.

Specify the version with the version 2 command

Specify each major network on which to run RIP with the network command.

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 4: (QID=25125)

You want to implement port-security on your 2960 but you don’t know all of the MAC addresses. How can you still enable port-security and protect the currently attached devices?

1. switch(config-if)#switchport port-security mac-address sticky

2. switch(config-if)#switchport port-security mac-address enable

3. switch(config-if)#switchport port-security mac-address learn

4. switch(config-if)#switchport port-security mac-address dynamic

---------------------------------------------

Correct answer(s): 1

Explanation: When we use the switchport port-security mac-address sticky interface configuration command the switch looks at the the header of the first frame to determine the mac-address of the host that is currently connected to that port.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 5: (QID=25121)

How do you enable ppp on a serial interface?

1. router(config)#ppp enable

2. router(config-if)#encapsulation ppp

3. router(config-if)#ppp enable

4. router(config-if)#no encapsulation hdlc

---------------------------------------------

Correct answer(s): 2

Explanation: The encapsulation ppp interface configuration command enables ppp on the interface.

[Implement and verify WAN links]

--------------------------------------------------------------------------------

Question 6: (QID=2368)

What command do we use if we want to discover other Cisco devices on the network?

1. Discover neighbors

2. Show neighbors

3. CDP run

4. CDP enable

---------------------------------------------

Correct answer(s): 3

Explanation: To enable Cisco Discovery Protocol (CDP), use the cdp run global configuration command. To disable CDP, use the no form of this command.

no cdp run

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 7: (QID=1323)

Spanning Tree is used in a switched network to:

1. Create a loop-free switched network

2. Manage a switched network

3. Avoid collisions on the switched network

4. Route between VLAN’s

---------------------------------------------

Correct answer(s): 1

Explanation: Spanning Tree is a technology that allows bridges to communicate with each other to discover physical loops in the network. The protocol then specifies an algorithm that bridges use to create a loop-free logical topology.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 8: (QID=3620)

What switching method is described by the following:

"The switch receives the entire frame and calculates a CRC. This method has high latency because of this behaviour."

1. Cut-Through

2. Cisco Express Forwarding

3. Fragment-Free

4. Store-and-Forward

---------------------------------------------

Correct answer(s): 4

Explanation: The Store-and-Forward switching mode receives the entire frame before beginning the switching process. When it receives the complete frame, the switch examines it for the source and destination addresses and any errors it may contain, and then it possibly applies any special filters created by the network administrator to modify the default behaviour. If the switch observes any errors in the frame, it is discarded, preventing errored frames from consuming bandwidth on the destination segment.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 9: (QID=2365)

What command is used during an IOS upgrade to place the IOS image on the router?

1. Show version

2. Copy TFTP: Flash:

3. Copy TFTP: RAM:

4. Copy running-config startup-config

---------------------------------------------

Correct answer(s): 2

Explanation: Router Memory Commands

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 10: (QID=2380)

Which command do we use to move from interface configuration mode to global configuration mode without exiting configuration mode?

1. Disable

2. Logout

3. End

4. Exit

---------------------------------------------

Correct answer(s): 4

Explanation: Click here for more information.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 11: (QID=25131)

In 802.11b, how many non-overlapping channels are available?

1. 1

2. 3

3. 5

4. 7

5. 11

---------------------------------------------

Correct answer(s): 2

Explanation: 802.11b has 3 non-overlapping channels, channel 1, 6 and 11

[Explain and select the appropriate administrative tasks required for a WLAN]

--------------------------------------------------------------------------------

Question 12: (QID=2999)

What command do we use if we want to see the output of our debugs during our session?

1. Show debug all

2. u all

3. Terminal monitor

4. Show all debug

---------------------------------------------

Correct answer(s): 3

Explanation: The terminal monitor command in EXEC mode will display all debug outputs and system error messages for the current terminal and session.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 13: (QID=2996)

You have lost telnet access to your switch which is located on-site. When trying to access the switch via the console port we are unable to get a connection going. Our terminal emulation program settings are: 9600 baud, 8N1, no flow-control. What could be the cause of the problem?

1. We are using a cross-over cable

2. We are using a roll-over cable

3. Our terminal emulation program is not configured correctly

4. The operating system on our PC/laptop is not compatible with Cisco

---------------------------------------------

Correct answer(s): 1

Explanation: In order to use the console port on a router we need to configure our Terminal Emulation program (Hyper Terminal, TerraTerm Pro, …) with the following parameters:

Baud rate: 9600

Data bits:8

Parity: none

Stop bits: 1

Flow control: none

The cable type we use is a cross-over cable. [Implement a small switched network]

--------------------------------------------------------------------------------

Question 14: (QID=25139)

What can we use to detect an attack that has a specific packet pattern?

1. Firewall

2. IPS

3. Anti-virus

4. URL filtering

5. DMZ

---------------------------------------------

Correct answer(s): 2

Explanation: An IPS, Intrusion Prevention System or IDS, Intrusion Detection System, is used to detect/prevent attacks that have a distinctive packet pattern.

[Identify security threats to a network and describe general methods to mitigate those threats]

--------------------------------------------------------------------------------

Question 15: (QID=1324)

According to the IEEE 802.3 standard, Ethernet can run on what type of media? [Select all that apply]

1. 10BaseF

2. 100BaseTX

3. 1000BaseF

4. 10Base5

5. 10Base4

---------------------------------------------

Correct answer(s): 1 4

Explanation: 10BaseT - Ethernet over Twisted Pair Media

10BaseF - Ethernet over Fiber Media

10Base2 - Ethernet over Thin Coaxial Media

10Base5 - Ethernet over Thick Coaxial Media

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 16: (QID=25127)

Which of the following encourages the interoperability of wireless products?

1. IEEE

2. FCC

3. Wi-Fi alliance

4. ITU-R

---------------------------------------------

Correct answer(s): 3

Explanation: The Wi-Fi alliance encourages the interoperability of wireless products using their Wi-Fi certified program.

[Explain and select the appropriate administrative tasks required for a WLAN]

--------------------------------------------------------------------------------

Question 17: (QID=2383)

Which of the following describes the correct order when a router is powered on?

1. Locate the IOS image, hardware is initialized, load configuration file, decompress the IOS image

2. Load configuration file, hardware is initialized, locate the IOS image, decompress the IOS image

3. Locate the IOS image, decompress the IOS image, hardware is initialized, load configuration file

4. Hardware is initialized, locate the IOS image, decompress the IOS image, load configuration file

---------------------------------------------

Correct answer(s): 4

Explanation: The boot sequence of a Cisco router is as follows:

ROM Monitor is the first to start and together with the BOOTSTRAP the following functions are performed:

Power-on register settings are configured

NVRAM and DRAM is tested

Hardware is initialized

Software structures are initialized

ROMmon looks for the IOS image in the flash

Once the IOS image is located the router decompresses it and loads it into DRAM. The IOS itself performs the following functions:

recognition of interfaces and other hardware

setting up proper data structures

allocating buffers

loading the configuration file from NVRAM to RAM

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 18: (QID=3680)

When our information is travelling down the OSI model what name do we give it when it reaches layer 3?

1. Frames

2. Segments

3. Bits

4. Packets

5. Data

---------------------------------------------

Correct answer(s): 4

Explanation: When user data travels through the OSI layers each layer adds its own information to the data. User data is called ‘Data’ at the application, presentation and session layer, when it moves through the transport layer it is called ‘Segments’. Packets can be found at the network layer of the OSI model. At layer 2 or Datalink layer we are talking about ‘Frames’ that will be put on the wire at the physical layer in the form of ‘Bits’.

[Describe the operation of data networks]

--------------------------------------------------------------------------------

Question 19: (QID=25135)

Which of the following are parts of a socket?

1. IP address

2. Transport protocol

3. Sequence number

4. Port number

---------------------------------------------

Correct answer(s): 1 2 4

Explanation: A socket has three parts:

IP Address

Transport protocol (TCP or UDP)

Port number

[Describe the operation of data networks]

--------------------------------------------------------------------------------

Question 20: (QID=3677)

What protocol is used to resolve MAC Addresses to a known IP Address?

1. ICMP

2. RARP

3. IGMP

4. ARP

---------------------------------------------

Correct answer(s): 4

Explanation: A host that wants to communicate with another host of which the IP Address is known will send out an ARP request to discover the MAC Address.

[Implement an IP addressing scheme and IP services to meet network requirements for a small branch office]

--------------------------------------------------------------------------------

Question 21: (QID=2338)

What type of connection do you recommended for the following scenario: The remote sites need fast downloads while their uploads to the head office can be slower, cost has to be taken into account.

1. ATM

2. ISDN

3. Frame-Relay

4. ADSL

---------------------------------------------

Correct answer(s): 4

Explanation: Asymmetric Digital Subscriber Line. One of four DSL technologies. ADSL is designed to deliver more bandwidth downstream (from the central office to the customer site) than upstream. Downstream rates range from 1.5 to 9 Mbps, whereas upstream bandwidth ranges from 16 to 640 kbps. ADSL transmissions work at distances up to 18,000 feet (5,488 meters) over a single copper twisted pair.

[Describe the operation of data networks]

--------------------------------------------------------------------------------

Question 22: (QID=3006)

One of the software engineers in the company wants to test a new application. When he connects the PC to a free port on the switch he does not get a link light. When he temporarily connects the PC to a different port there is a link light. What is the most likely cause of this problem?

1. The NIC in the PC is 100Mb and the switch port is configured for 10MB

2. All the switch ports are faulty

3. The application is not working properly

4. The cable is faulty

---------------------------------------------

Correct answer(s): 1

Explanation: Because there is a speed mismatch between the PC and the switch port a link will not be established.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 23: (QID=2376)

We want to configure a password in order to secure the Privileged EXEC mode? Which of the following are commands we can use?

1. Password enable password

2. Enable password password

3. Secret Password password

4. Enable Secret password

---------------------------------------------

Correct answer(s): 2 4

Explanation: To set a local password to control access to various privilege levels, use the enable password command in global configuration mode. To specify an additional layer of security over the enable password command, use the enable secret command in global configuration mode.

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 24: (QID=2373)

We want to know which routing protocols are active on the router. Which command do we use?

1. Show IP Protocols

2. Show IP Routing Protocols

3. Show Active Protocols

4. Show IP Active Protocols

---------------------------------------------

Correct answer(s): 1

Explanation: To display the parameters and current state of the active routing protocol process, use the show ip protocols command in privileged EXEC mode.

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 25: (QID=3611)

Users complain that they are not able access resources at the head office. You ping a few hosts on the head office LAN and the responses are all unsuccessful. What would be the next step you do to locate the problem?

1. Use the trace route utility

2. Reboot the router

3. Clear the routing table

4. Replace the faulty router

---------------------------------------------

Correct answer(s): 1

Explanation: When we use the trace route utility to one of the IP Addresses we pinged we will find out at which hop the problem lies. We then can continue our troubleshooting from that point.

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 26: (QID=2988)

Which of the following commands would you use to troubleshoot a routing problem?

1. Show version

2. Show IP route

3. Show IP interface brief

4. Ping

5. Show users

6. Traceroute

7. Show hosts

8. Show history

---------------------------------------------

Correct answer(s): 2 4 6

Explanation: When troubleshooting a routing issue we usually start by ‘pinging’ a host on the remote network we try to reach. If we don’t get a response back we check the routing table to see if we have a route to the remote network. If there is a route we do a ‘traceroute’ to the remote network to find out at which hop the possible cause of the problem might lie.

Understanding the Ping and Traceroute Commands Troubleshooting Tools

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 27: (QID=2989)

What command do we use to show us all the RIP entries in the routing table but no other routes?

1. Show ip route

2. Show ip rip route

3. Show rip route

4. Show ip route rip

---------------------------------------------

Correct answer(s): 4

Explanation: The show ip route command can be ‘extended’ with the name of the routing protocol running on the router. Adding the name of the routing protocol displays only entries of that protocol in the routing table.

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 28: (QID=25132)

Which of the following wireless parameters has to be the same on both the client and AP?

1. SSID

2. ESS

3. radio power setting

4. BSS

---------------------------------------------

Correct answer(s): 1

Explanation: In order to get an association with the AP the SSID, Service Set Identifier, has to be same on the AP and wireless client.

[Explain and select the appropriate administrative tasks required for a WLAN]

--------------------------------------------------------------------------------

Question 29: (QID=3683)

viewimage

Look at the network topology in the exhibit. How many collision domains are there?

1. 1

2. 2

3. 3

4. 4

5. 5

6. 6

---------------------------------------------

Correct answer(s): 5

Explanation: A Collision Domain is defined as all of the Ethernet segments between a pair of bridges or other layer 2 devices.

coldom2

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 30: (QID=2367)

After making configuration changes, you want to save them. What command do you use? [Select best answer]

1. Save config

2. write memory

3. Copy startup-config running-config

4. Copy running-config startup-config

---------------------------------------------

Correct answer(s): 4

Explanation: Copy running-config startup-config will save your changes to NVRAM. Although write memory will do the same thing it is better to use the copy command.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 31: (QID=1295)

RIP Version 2 uses which multicast address to update its routing tables.

1. 224.0.0.10

2. 224.0.0.5

3. 224.0.0.1

4. 224.0.0.9

---------------------------------------------

Correct answer(s): 4

Explanation: More information about RIP version 2 can be found at RIP Version 2 RFC 2453. The other multicast addresses are used by different routing protocols (EIGRP, OSPF).

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 32: (QID=25146)

Which proprietary Cisco field is added to the HDLC standard frame?

1. Type

2. Flag

3. Destination

4. Control

---------------------------------------------

Correct answer(s): 1

Explanation: Cisco added a type field to the HDLC standard frame to make it Cisco proprietary.

[Implement and verify WAN links]

--------------------------------------------------------------------------------

Question 33: (QID=2377)

What command do we use to show us a summary of the all the interfaces on a router?

1. Show IP interface brief

2. Show interfaces all

3. Show IP interface detail

4. Show interfaces brief

---------------------------------------------

Correct answer(s): 1

Explanation: The show ip interface brief command will give you all the interfaces of the router and their status, IP Address, etc… This command can be useful troubleshooting tool if you quickly want to view the interface details.

click here for sample output of this command.

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 34: (QID=3623)

Which switching method will store the first 64 bytes of the packet?

1. Store-and-Forward

2. Cut-Through

3. Cisco Express Forwarding

4. Fragment-Free

---------------------------------------------

Correct answer(s): 4

Explanation: A less common method is fragment-free. It works like cut-through but stores the first 64 bytes of the packet before sending it on. The reason for this is that most errors and all collisions occur during the initial 64 bytes of a packet.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 35: (QID=2358)

When implementing a switched network we have to make sure that the following is running?

1. VTP Pruning

2. IGMP

3. A routing protocol

4. Spanning Tree

---------------------------------------------

Correct answer(s): 4

Explanation: Spanning tree will provide a loop free switched environment.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 36: (QID=3624)

Which port does TFTP use?

1. 53

2. 21

3. 69

4. 20

---------------------------------------------

Correct answer(s): 3

Explanation: TFPT uses port 69. Well-known Port Numbers

[Describe the operation of data networks]

--------------------------------------------------------------------------------

Question 37: (QID=1285)

What is the administrative distance of the following Static Route:

IP Route 192.168.3.0 255.255.255.0 Serial0/1

1. 1

2. 110

3. 0

4. 255

5. 170

---------------------------------------------

Correct answer(s): 3

Explanation: Static routes using an exit interface have an administrative distance of 0. Administrative Distance.

[Implement a small routed network]

--------------------------------------------------------------------------------

Question 38: (QID=25129)

Which two modes exist in a wireless network?

1. Ad-hoc mode

2. Peer-to-peer mode

3. Shared mode

4. Infrastructure mode

---------------------------------------------

Correct answer(s): 1 4

Explanation: Wireless networks operate either in Ad-Hoc mode or Infrastructure mode.

[Explain and select the appropriate administrative tasks required for a WLAN]

--------------------------------------------------------------------------------

Question 39: (QID=3631)

In which of the following configurations would you use a crossover cable?

1. Host to switch

2. Switch to router

3. Host to router

4. Hub to Switch

5. Hosts to hub

---------------------------------------------

Correct answer(s): 3 4

Explanation: Crossover cables can be used in the following situations:

to connect 2 hosts together

to connect 2 switches or hubs

to connect a router to a host

Modern switches come with MDIX ports but the speed and duplex setting must remain on auto.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 40: (QID=3694)

We need a minimum of 2500 hosts on each of the subnets. Our network address is 10.0.0.0/8. What is the subnet mask?

1. 255.255.224.0

2. 255.255.248.0

3. 255.255.240.0

4. 255.255.192.0

---------------------------------------------

Correct answer(s): 3

Explanation: To provide 2500 hosts on each subnet we need 12 bits available for host addressing.

Following the rules: 2^12 – 2 = 4096 – 2 = 4094 possible hosts on each subnet. Now we have 12 bits available for the subnet mask or in binary 1111 1111.1111 1111.1111 0000. The first 8 bits are from the default subnet mask of the network, convert the previous into decimal and it gives us 255.255.240.0 or /20.

[Implement an IP addressing scheme and IP services to meet network requirements for a small branch office]

--------------------------------------------------------------------------------

Question 41: (QID=2974)

We want to see a summary of the VLANs configured on our Catalyst 2960 switch. What command do we use?

1. Show vlan

2. Show vlan summary

3. Show vlan detail

4. Show vlan brief

---------------------------------------------

Correct answer(s): 4

Explanation: The show vlan brief command displays one line for each of the VLANs configured on the switch. The line contains the VLAN name, status and port membership.

[Implement a small switched network]

--------------------------------------------------------------------------------

Question 42: (QID=3695)

Given the following network 172.16.1.0/26. How many hosts do we have available on each of the subnets?

1. 62

2. 4096

3. 64

4. 128

---------------------------------------------

Correct answer(s): 1

Explanation: /26 or 255.255.255.192 leaves us 6 bits for possible hosts on each subnet. Following the rule for hosts 2^n -2 = available hosts, 2^6 – 2 = 64 – 2 = 62 hosts. The -2 is to deduct the network address and the broadcast address of the subnet.

[Implement an IP addressing scheme and IP services to meet network requirements for a small branch office]

--------------------------------------------------------------------------------

Question 43: (QID=1481)

We need 30 hosts on each of the subnets we create from the following network 192.168.3.0/24. What is the correct subnet mask?

1. 255.255.0.0

2. 255.255.255.0

3. 255.255.252.0

4. 255.255.255.224

---------------------------------------------

Correct answer(s): 4

Explanation: We need 30 hosts on each subnet and in order to accommodate those we need 5 bits of the last octet to be allocated to hosts 2^5 -2 = 30. This leaves us 3 bits for the available subnets 2^3 = 8 subnets. In binary that becomes 111, first 3 bits for the subnet or 224 and the remaining 5 positions for the hosts on each subnet.

[Implement an IP addressing scheme and IP services to meet network requirements for a small branch office]

--------------------------------------------------------------------------------

Question 44: (QID=1281)

RFC1918 specifies the allocation of IP Addresses for Private Internetworks. What are they?

1. 10.0.0.0 - 10.255.255.255

2. 192.168.0.0 - 192.168.255.255

3. 172.16.0.0 - 172.32.0.0

4. 172.16.0.0 – 172.31.255.255

5. 192.169.0.0 - 192.169.255.255

---------------------------------------------

Correct answer(s): 1 2 4

Explanation: 10.0.0.0, 172.16.0.0 – 172.31.255.255 and 192.168.0.0 are the IP Address ranges that must be used in private internetworks. These address ranges are not routed on the internet. To find out more about this: RFC1918.

[Implement an IP addressing scheme and IP services to meet network requirements for a small branch office]

--------------------------------------------------------------------------------

Question 45: (QID=25130)

When we have more than one AP in our infrastructure mode it is called?

1. BSS

2. ESS

3. CSS

4. EBSS

---------------------------------------------

Correct answer(s): 2

Explanation: A extended service set or ESS is created when we use more than one AP with overlap in infrastructure mode.

[Explain and select the appropriate administrative tasks required for a WLAN]

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Question 46: (QID=3614)

We notice a huge number of FCS errors on one of the switch ports that is running in full-duplex mode. What could be the cause of this?

1. Faulty switch port

2. Faulty cable

3. It is normal to have FCS errors in full-duplex mode

4. The switch is running out of memory

5. Software/hardware issues with the NIC

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Correct answer(s): 1 2 5

Explanation: In full-duplex mode the collision counter is not active. If the FCS, CRC errors increment then the most likely cause is a duplex mismatch. Other causes can be a faulty cable, a faulty switch port or hardware/software issues with the NIC.

[Implement a small switched network]

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Question 47: (QID=2970)

We have acquired a new Catalyst 3550 switch with Enhanced IOS image. What command allows us to remotely manage that switch using Cisco’s defaults?

A) Switch(config)#interface vlan1

Switch(config-if)#ip address 10.1.1.5 255.255.255.0

B) Switch(config)#interface fastethernet0/1

Switch(config-if)#ip address 10.1.1.5 255.255.255.0

C) Switch(config)#interface vlan1

Switch(config-vlan)#ip address 10.1.1.5 255.255.255.0

D) Switch(config)#interface ip 10.1.1.5 255.255.255.0

1. A

2. B

3. C

4. D

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Correct answer(s): 1

Explanation: We assign an ip address to the default management VLAN 1 using interface configuration mode. By default the management VLAN is 1 but it can be any VLAN between 1 to 1001.

[Implement a small switched network]

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Question 48: (QID=2369)

We want to try a new IOS release but we don’t have enough space on our Flash memory to hold both IOS’s. What needs to be done to use the new image?

1. Add the following line to the configuration: no boot system flash [filename]

2. Add the following line to the configuration: boot system tftp [filename] [ip address]

3. Add the following line to the configuration: no boot system rom

4. This can not be done; we need to upgrade the IOS

---------------------------------------------

Correct answer(s): 2

Explanation: To specify the system image that the router loads at startup, use one of the following boot system global configuration commands. To remove the startup system image specification, use the no form of the command.

boot system file-url

no boot system file-url

boot system flash [flash-fs:][partition-number:][filename]

no boot system flash [flash-fs:][partition-number:][filename]

boot system mop filename [mac-address] [interface]

no boot system mop filename [mac-address] [interface]

boot system rom

no boot system rom

boot system {rcp | tftp | ftp} filename [ip-address]

no boot system {rcp | tftp | ftp} filename [ip-address]

no boot system

[Implement a small routed network]

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Question 49: (QID=1478)

What is the maximum cable length for UTP cable?

1. 185m

2. 2000m

3. 100m

4. 500m

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Correct answer(s): 3

Explanation: 10 BaseT & 100 BaseT 100m

10 Base2 185m

10 Base5 500m

10 BaseFL 2000m

[Describe the operation of data networks]

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Question 50: (QID=25147)

Which ppp protocol is used to test the data link connection?

1. UDP

2. Q.931

3. NCP

4. LCP

---------------------------------------------

Correct answer(s): 4

Explanation: LCP or Link Control Protocol is used in the PPP protocol suite to test the data link connection.

[Implement and verify WAN links]

test me

Etherchannel Concept and configuration

EtherChannel vs. 802.3ad

Cisco Lab

Rapid spanning tree protocol (RSTP)

PVST -- Cisco’s RSTP Implementation

Cisco Lab

LAN vs VLAN

VLAN membership

VLAN to VLAN communication

VLAN trunks

Cisco lab

Root Bridges

Bridge Protocol Data Units (BPDUs)

Root Ports

Designated Ports

Lesson 1Introduction to Networking and the Networking Models

Lesson 1
Introduction to Networking and the Networking Models