IP Routing Questions

1. A router has two FastEthernet interfaces and needs to connect to four vlans in the local network. How can you accomplish this task, using the fewest physical interfaces and without decreasing network performance?

Add two more FastEthernet interfaces.

Add a second router to handle the vlan traffic.

Use a hub to connect the four vlans with a FastEthernet interface on router.

Implement a router-on-a-stick configuration.

2. Refer to the graphic.

Host A is communicating with the server. What will be the source MAC address of the frames received by Host A from the server?

The MAC address of router interface e0

The MAC address of router interface e1

The MAC address of the server network interface

The MAC address of host A

3. A router has learned three possible routes that could be used to reach a destination network. One route is from EIGRP and has a composite metric of 20514560. Another route is from OSPF with a metric of 782. The last is from RIPv2 and has a metric of 4. Which route or routes will the router install in the routing table?

The OSPF route

The EIGRP route

The RIPv2 route

All three routes

The OSPF and RIPv2 routes

When one route is advertised by more than one routing protocol, the router will choose to use the routing protocol which has lowest Administrative Distance. The Administrative Distances of popular routing protocols are listed below:

Explanation

When one route is advertised by more than one routing protocol, the router will choose to use the routing protocol which has lowest Administrative Distance. The Administrative Distances of popular routing protocols are listed below:

4. A router receives information about network 192.168.10.0/24 from multiple sources. What will the router consider the most reliable information about the path to that network?

An OSPF update for network 192.168.0.0/16

A static router to network 192.168.10.0/24

A static router to network 192.168.10.0/24 with a local serial interface configured as the next hop

A RIP update for network 192.168.10.0/24

A directly connected interface with an address of 192.168.10.254/24

A default route with a next hop address of 192.168.10.1

5. Refer to the exhibit, Host A pings interface S0/0 on router 3, what is the TTL value for that ping?

253

252

255

254

From the CCNA ICND2 Exam book: “Routers decrement the TTL by 1 every time they forward a packet; if a router decrements the TTL to 0, it throws away the packet. This prevents packets from rotating forever.” I want to make it clear that before the router forwards a packet, the TTL is still remain the same. For example in the topology above, pings to S0/1 and S0/0 of Router 2 have the same TTL. The picture below shows TTL values for each interface of each router and for Host B. Notice that Host A initializes ICMP packet with a TTL of 255:

Explanation

From the CCNA ICND2 Exam book: “Routers decrement the TTL by 1 every time they forward a packet; if a router decrements the TTL to 0, it throws away the packet. This prevents packets from rotating forever.” I want to make it clear that before the router forwards a packet, the TTL is still remain the same. For example in the topology above, pings to S0/1 and S0/0 of Router 2 have the same TTL. The picture below shows TTL values for each interface of each router and for Host B. Notice that Host A initializes ICMP packet with a TTL of 255:

6. Refer to the exhibit. A network administrator attempts to ping Host2 from Host1 and receives the results that are shown. What is a possible problem?

The link between Host1 and Switch1 is down.

TCP/IP is not functioning on Host1

The link between Router1 and Router2 is down.

The default gateway on Host1 is incorrect.

Interface Fa0/0 on Router1 is shutdown.

The link between Switch1 and Router1 is down.

In this question, Host1 wants to ping Host2 but it receives a reply from the interface Fa0/0 of Router1 (10.1.1.1/24) that the “destination host unreachable”.

If the link between Host1 and Switch1 is down or the link between Switch1 and Router1 is down then Host1 can not receive this reply -> A and F are not correct.

Host1 can receive a reply from 10.1.1.1 -> the TCP/IP is working properly -> B is not correct.

For answer D, if the default gateway was not configured correctly on Host1 (in this case the default gateway should be 10.1.1.1/24) then 10.1.1.1 can not receive the ping packets from Host1 and can not reply for Host1 that the destination is unreachable -> D is not correct.

Interface Fa0/0 on Router1 replies for the ping packets from Host1 so it is up -> E is not correct. If the interface Fa0/0 on Router is shutdown then we will receive a message of “Request timed out”, not “Destination host unreachable”.

Answer C is correct because we can get a reply from the interface Fa0/0 of Router1 so the link between Host1 and Router1 should be fine -> the problem lies at the other side of Router1. But if the link between Router2 and Host2 is down then we will receive a reply from interface S0/1 of Router2 that the “destination host unreachable”. Therefore the problem can just be the link between Router1 and Router2.

Explanation

In this question, Host1 wants to ping Host2 but it receives a reply from the interface Fa0/0 of Router1 (10.1.1.1/24) that the “destination host unreachable”.

If the link between Host1 and Switch1 is down or the link between Switch1 and Router1 is down then Host1 can not receive this reply -> A and F are not correct.

Host1 can receive a reply from 10.1.1.1 -> the TCP/IP is working properly -> B is not correct.

For answer D, if the default gateway was not configured correctly on Host1 (in this case the default gateway should be 10.1.1.1/24) then 10.1.1.1 can not receive the ping packets from Host1 and can not reply for Host1 that the destination is unreachable -> D is not correct.

Interface Fa0/0 on Router1 replies for the ping packets from Host1 so it is up -> E is not correct. If the interface Fa0/0 on Router is shutdown then we will receive a message of “Request timed out”, not “Destination host unreachable”.

Answer C is correct because we can get a reply from the interface Fa0/0 of Router1 so the link between Host1 and Router1 should be fine -> the problem lies at the other side of Router1. But if the link between Router2 and Host2 is down then we will receive a reply from interface S0/1 of Router2 that the “destination host unreachable”. Therefore the problem can just be the link between Router1 and Router2.

7. Refer to the exhibit. The network administrator requires easy configuration options and minimal routing protocol traffic. Which two options provide adequate routing table information for traffic that passes between the two routers and satisfy the requests of the network administrator? (choose two)

A dynamic routing protocol on InternetRouter to advertise summarized routers to CentralRouter.

A dynamic routing protocol on CentralRouter to advertise summarized routers to InternetRouter.

A static route on InternetRouter to direct traffic that is destined for 172.16.0.0/16 to CentralRouter.

A dynamic routing protocol on InternetRouter to advertise all routes to CentralRouter.

A dynamic routing protocol on CentralRouer to advertise all routes to InternetRouter

A static, default route on CentralRouter that directs traffic to InternetRouter.

Submit

8. Refer to the graphic. A static route to the 10.5.6.0/24 network is to be configured on the HFD router. Which commands will accomplish this? (Choose two)

HFD (config) #ip route 10.5.6.0 0.0.0.255 fa0/0

HFD(config)# ip route 10.5.6.0 0.0.0.255 10.5.4.6

HFD(config)# ip route 10.5.6.0 255.255.255.0 fa0/0

HFD(config)# ip route 10.5.6.0 255.255.255.0 10.5.4.6

HFD(config)# ip route 10.5.4.6 0.0.0.255 10.5.6.0

HFD(config)# ip route 10.5.4.6 255.255.255.0 10.5.6.0

The simple syntax of static route:

ip route destination-network-address subnet-mask {next-hop-IP-address | exit-interface}
+ destination-network-address: destination network address of the remote network
+ subnet mask: subnet mask of the destination network
+ next-hop-IP-address: the IP address of the receiving interface on the next-hop router
+ exit-interface: the local interface of this router where the packets will go out

In the statement “ip route 10.5.6.0 255.255.255.0 fa0/0″:

+ 10.5.6.0 255.255.255.0: the destination network
+ fa0/0: the exit-interface

Explanation

The simple syntax of static route:

ip route destination-network-address subnet-mask {next-hop-IP-address | exit-interface}
+ destination-network-address: destination network address of the remote network
+ subnet mask: subnet mask of the destination network
+ next-hop-IP-address: the IP address of the receiving interface on the next-hop router
+ exit-interface: the local interface of this router where the packets will go out

In the statement “ip route 10.5.6.0 255.255.255.0 fa0/0″:

+ 10.5.6.0 255.255.255.0: the destination network
+ fa0/0: the exit-interface

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9. If IP routing is enabled, which two commands set the gateway of last resort to the default gateway? (Choose two)

Ip default-gateway 0.0.0.0

Ip route 172.16.2.1 0.0.0.0 0.0.0.0

Ip default-network 0.0.0.0

Ip default-route 0.0.0.0 0.0.0.0 172.16.2.1

Ip route 0.0.0.0 0.0.0.0 172.16.2.1

Submit