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IP Routing

February 6th, 2017 Go to comments

Question 1

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:

EIGRP_Administrative Distances_popular_routing_protocols.jpg

Question 2

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 192.168.0.0 255.255.240.0 GigabitEthernet0/1″:

+ 192.168.0.0 255.255.240.0: the destination network
+ GigabitEthernet0/1: the exit-interface

Question 3

Question 4

Explanation

The static routing specifies a fixed destination so it is “consistent”. It is best used for small-scaled places where there are a few routers only. When links fail, static route cannot automatically find an alternative path like dynamic routing so routing is disrupted.

Question 5

Explanation

Host Z will use ARP to get the MAC address of the interface on R1 that connects to it and use this MAC as the destination MAC address. It use the IP address of the storage server as the destination IP address.

For example in the topology below, host A will use the MAC address of E0 interface of the router as its destination MAC address to reach the Email Server.

destination_addresses.jpg

Question 6

Explanation

The Administrative Distance (AD) of popular routing protocols is shown below. You should learn them by heart:

EIGRP_Administrative Distances_popular_routing_protocols.jpg

Note: The AD of iBGP is 200

The smaller the AD is, the better it is. The router will choose the routing protocol with smallest AD.

In this case EIGRP with AD of 90 is the smallest one.

Question 7

Question 8

Question 9

Explanation

The Layer 2 information (source and destination MAC) would be changed when passing through each router. The Layer 3 information (source and destination IP addresses) remains unchanged.

Question 10

Question 11

Question 12

Question 13

Explanation

The administrative distance of each protocol is compared to see if that route is better or not.

Question 14

Explanation

Letter “D” is used to symbolize for EIGRP (with a default AD of 90). Letter “E” is not used for EIGRP because it has been used for Exterior Gateway Protocol (EGP). It is a now obsolete routing protocol.

Question 15

Comments (11) Comments
  1. Ppetro
    February 7th, 2017

    Question 9 – correct answer is B. Router works in layer 3 and makes changes in Layer 3 IP address.
    In question we can find word ” packet ” so for me is also a tip which indicates B as correct answer

  2. Tepi
    February 8th, 2017

    Q9 .. the question is not well worded. I think it is using “packet’ in its general sense (datagram) so answer A would be correct (Layer 2 frame header and trailer). Also the router does not “replace the Layer 3 IP address” – the IP address of the packet is untouched.

  3. Tepi
    February 8th, 2017

    Q8 … “Which component of a routing table entry represents the subnet mask?” The routing table does not mention the network mask only the prefix .. so I think B is the correct answer ?

    10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
    C 10.0.0.0/30 is directly connected, GigabitEthernet0/0
    L 10.0.0.1/32 is directly connected, GigabitEthernet0/0
    192.168.0.0/24 is variably subnetted, 4 subnets, 2 masks
    C 192.168.0.0/28 is directly connected, Loopback0
    L 192.168.0.1/32 is directly connected, Loopback0
    C 192.168.0.48/28 is directly connected, Loopback1
    L 192.168.0.49/32 is directly connected, Loopback1

  4. Ppetro
    February 8th, 2017

    @Tepi – I read this question once again and… yeap – you have right. Correct answer is A.
    I thought is a tricky question :P

  5. Ppetro
    February 8th, 2017

    @Tepi – I believe you have right regarding to Q8 – correct answer should be B

  6. Star
    February 21st, 2017

    Regarding Q8 . I agree with @Tepi it should be B

  7. Anonymous
    March 2nd, 2017

    Where are question?

  8. jasin
    March 8th, 2017

    hi basically when you click on link to check your knowledge that time it show only 4 questions on this particular tab ip- routing check it out thanks

  9. Yo
    March 11th, 2017

    Yep, that’s what I thought guys, question 8 should be B, but maybe we’re missing something. Can anyone correct us and explain if we’re wrong? Thank you..

  10. AS1997
    March 20th, 2017

    im a premium member and when i click on the link for the questions there are only four questions coming up while there is 15 questions on the 9tut for ip routing is there any specific reason for this 9tut???

  11. Mhnd85
    March 20th, 2017

    The same question has been asked from AS1997