Latest CCNP Routing Interview Questions Part – 3

1.Compare IS-IS metrics with OSPF metrics.

An OSPF interface metric is determined from the interface bandwidth. By default,all IS¬-IS interface metrics are equal to
10. Therefore,the EIGRP route is preferred.

2.What is the difference between an IS-IS narrow and wide metric?

A narrow metric uses 6 bits for the interface metric and 10 bits for the path metric. A wide metric uses 24 bits for the interface metric and 32 bits for the path metric.

3.What types of routes are allowed into a stub area?

OSPF intra-area and inter area routes,and a default route. External routes are not advertised into a stub area.

4.What types of routes are allowed into a totally stubby area?

OSPF intra-area routes and a default route. OSPF inter area and external routes are not advertised into a totally stubby area.

5.What types of routes are allowed into a NSSA?

OSPF intra-area and inter area routes,and possibly a default route. External routes from ABRs are blocked,and external routes from ASBRs are converted to Nl or N2 routes.

6.What types of routes are allowed into a totally NSSA?

OSPF intra-area routes and a default route. External routes from ABRs are blocked,and external routes from ASBRs are converted to Nl or N2 routes.

7.What is the difference between an El and E2 OSPF route?

An El route contains the OSPF cost to reach the ASBR plus the cost from the ASBR to the external route. An E2 route contains only the cost from the ASBR to the external route.

8.What are the three types of OSPF routers?

ABR,internal router,and ASBR.

9.What are the six OSPF route types?

Intra-area,inter area,El,E2,Nl,and N2.

10.Where can routes be summarized in an OSPF network?

OSPF routes are summarized on an ABR. External routes are summarized on an ASBR.

11.How is the OSPF router ID determined?

If physical interfaces are only used,the OSPF router id is the highest IP address assigned to an active physical interface. If loopback interfaces are used,the OSPF router ID is the highest IP address assigned to a loopback interface. If the router-id command is used with the OSPF configuration,the address used with this command will be the router id.

12.How does OSPF determine the DR on a multi-access network?

The router with the highest interface priority will be the router ID. If all the interface priorities on the multi-access network are the same,the router with the highest router ID will be the DR.

13.How does OSPF determine an inter area shortest path?

First,calculate the shortest path to an ABR.Second,calculate the shortest path across area 0 to an ABR that is attached to the destination area.Third,calculate the shortest path across the destination area from the ABR to the destination network.

14.What is the purpose of an OSPF virtual link?

To connect a nonzero area to the backbone if the nonzero area becomes disconnected from the backbone. A virtual link can also be used if the backbone,or area 0,becomes discontiguous.

15.How is the OSPF cost of an interface calculated?

By default,the cost of an OSPF interface is 1 OO,OOO,OOO/(Interface Bandwidth). The constant 100,000,000 can be changed using the auto-cost reference-bandwidth command.

16.The following OSPF routes originate in OSPF area 1: 18
8.1
4.1
9.0/28 18
8.1
4.1
9.16/28 18
8.1
4.1
9.32/28 18
8.1
4.1
9.48/28 What is the command to summarize these routes on the ABR between area 1 and the backbone?

Area 1 range 18
8.1
4.1
9.0 25
5.25
5.25
5.192

17.Why are intra-area summary routes not allowed?

OSPF databases on routers in the same area must be identical. If route summarization was allowed within an area,some routers would have specific routes and some routers would have summary routes for routers in the area. If this were allowed,the databases for the area would never agree.

18.Using the following routing table,determine the best route to reach the host at address 13
2.1
9.23
7.
5. Network Output Interface 13
2.0.0.0/8 Serial 0 13
2.1
6.0.0/11 Ethernet 1 13
2.1
6.23
3.0/22 Ethernet 2

13
2.1
6.0.0/11 because it matches more network bits than 13
2.0.0.0/
8. Network 13
2.1
6.23
3.0/22 and 13
2.1
9.23
7.5/22 do not match on the network address.

19.What is the range of host addresses for network 17

2.1
6.5
3.96/27?

17
2.1
6.5
3.97 through 17
2.1
6.5
3.12
6.

20.How many two-host subnets can be made from a /24 network?

64 because 2 bits are needed for the hosts on the network,leaving 6 bits for the subnet.

21.What is the full IPv6 address represented by FF02::130F:5?

FF02:0000:0000:0000:0000:0000: 130F:0005 .

22.Explain the difference between a classful and a classless routing protocol.

Classless routing protocols advertise subnet mask information along with the network prefixes. Classful routing protocols do not. Therefore,for a c1assful protocol,all subnets for the major network number being used must be the same length. Also,c1assful protocol cannot support discontiguous networks prefixes.

23.What are the states that an EIGRP route can be in and what do these states mean?

The passive state means that a router has a successor for a route. The active state means that a router does not have a successor or feasible successor for a route and is actively sending queries to neighbours to get information about the route.

The reported distance to a route that is sent to another router is the feasible distance on the reporting router. Feasible distance is the reported distance plus the metric between the receiving and reporting routers. The route with the lowest feasible distance is the successor. Any routes with a reported distance that is less than the feasible distance are feasible successors.

25.Determine the EIGRP command to summarize the following networks:

10.
1.0.0/19 >
10.
1.3
2.0/19
10.
1.6
4.0/19
10.
1.9
6.0/19

You need to examine the third byte because that is the byte where the four prefixes differ: 0=00000000 32 = 0 0 1 0 0 0 0 0 64=01000000 96 = 0 1 1 0 0 0 0 0 The last 7 bits are irrelevant,so the mask is 1 0 0 0 0 0 0 0 and the EIGRP command is ip summary-address eigrp 1
10.
1.0.025
5.25
5.12
8.0.

26.What are the purposes of areas in an OSPF network?

Areas allow the design of a hierarchical network. Routes can be summarized or blocked in an area to reduce the amount of routing information on internal OSPF routers.

27.What is the purpose of a default route?

A default route is used if there is not a specific entry in the routing table for the destination.

28.Describe the difference between routing and switching.

Routing moves a letter or telephone call to the access layer.Switching makes the final delivery. A switching decision is made on the part of the address that is not used in routing.