Networking - IP Routing

Exercise :: IP Routing - IP Routing

  • IP Routing - IP Routing
11. 

What is route poisoning?

A. It sends back the protocol received from a router as a poison pill, which stops the regular updates.
B. It is information received from a router that can't be sent back to the originating router.
C. It prevents regular update messages from reinstating a route that has just come up.
D. It describes when a router sets the metric for a downed link to infinity.

Answer: Option D

Explanation:

Another way to avoid problems caused by inconsistent updates and to stop network loops is route poisoning. When a network goes down, the distance-vector routing protocol initiates route poisoning by advertising the network with a metric of 16, or unreachable (sometimes referred to as infinite).

12. 

Which of the following is true regarding RIPv2?

A. It has a lower administrative distance than RIPv1.
B. It converges faster than RIPv1.
C. It has the same timers as RIPv1.
D. It is harder to configure than RIPv1.

Answer: Option C

Explanation:

RIPv2 is pretty much just like RIPv1. It has the same administrative distance and timers and is configured just like RIPv1.

13. 

A network administrator views the output from the show ip route command. A network that is advertised by both RIP and IGRP appears in the routing table flagged as an IGRP route. Why is the RIP route to this network not used in the routing table?

A. IGRP has a faster update timer.
B. IGRP has a lower administrative distance.
C. RIP has a higher metric value for that route.
D. The IGRP route has fewer hops.

Answer: Option B

Explanation:

RIP has an administrative distance (AD) of 120, while IGRP has an administrative distance of 100, so the router will discard any route with a higher AD than 100.

14. 

What does RIPv2 use to prevent routing loops?

  1. CIDR
  2. Split horizon
  3. Authentication
  4. Classless masking
  5. Holddown timers

A. 1 and 3
B. 2, 3 and 5
C. 2 and 5
D. 3 and 4

Answer: Option C

Explanation:

RIPv2 uses the same timers and loop-avoidance schemes as RIPv1. Split horizon is used to stop an update from being sent out the same interface it was received on. Holddown timers allow time for a network to become stable in the case of a flapping link.

15. 

Which two of the following are true regarding the distance-vector and link-state routing protocols?

  1. Link state sends its complete routing table out all active interfaces on periodic time intervals.
  2. Distance vector sends its complete routing table out all active interfaces on periodic time intervals.
  3. Link state sends updates containing the state of its own links to all routers in the internetwork.
  4. Distance vector sends updates containing the state of its own links to all routers in the internetwork.

A. 1 only
B. 3 only
C. 2 and 3 only
D. None of the above

Answer: Option C

Explanation:

The distance-vector routing protocol sends its complete routing table out all active interfaces at periodic time intervals. Link-state routing protocols send updates containing the state of its own links to all routers in the internetwork.