OSPF

Question 1

What are the criteria for DR / BDR election?

Answer 1

Priority, Highest RID

Question 2

With what priority does a router not participate in the DR / BDR election?

Answer 2

0

Question 3

OSPF multicast addresses?

Answer 3

224.0.0.5 All routers, 224.0.0.6 DR routers

Question 4

What are the OSPF timers for broadcast and point-to-point networks? (both use the same timers)

Answer 4

hello 10, dead 40

Question 5

Does OSPF support keys with lifetime?

Answer 5

False

Question 6

What are the OSPF timers for NBMA networks, PMPe PMP NBMA?

Answer 6

30 120

Question 7

What is the only network type where dynamic neighbor discovery does not occur?

Answer 7

NBMA

Question 8

What are the only two network types that require DR/BDR?

Answer 8

Broadcast and Non-Broadcast Multi-Access, both multi-access

Question 9

Which LSA is created by the DR?

Answer 9

Type 2 network, sh ip ospf database network

Question 10

Which command allows viewing type 3 LSA?

Answer 10

show ip ospf database summary

Question 11

Which command to view type 5 and type 4 LSAs?

Answer 11

show ip ospf database external, show ip ospf database asbr-summary

Question 12

Neighbor in Attempt state?

Answer 12

Neighbor defined manually

Question 13

What is the neighbor state when the first hello is received but the own RID is not yet listed?

Answer 13

init

Question 14

What is the neighbor state when the hello is received and the own RID is listed?

Answer 14

2way

Question 15

In which state does the master and slave negotiation occur?

Answer 15

exstart

Question 16

In which state does the DDP exchange occur?

Answer 16

exchange

Question 17

DDP is exchanged only for information between DROTHERS

Answer 17

False

Question 18

Describe what happens in a broadcast network when a DROther’s link changes

Answer 18

The DROTHER originates LSA 1 for the DR, DR propagates via DDP to the DROTHERS, The DROTHERS request it from the DR via LSR, The DR delivers via LSU, The DROTHERS confirm via LSACK

Question 19

What is the reflood period for LSAs?

Answer 19

30 minutes

Question 20

What is the maximum ECMP path supported?

Answer 20

4 paths, modern IOS 16 to 32

Question 21

Which LSAs cause SPF recalculation?

Answer 21

1 and 2

Question 22

How to filter LSA 3 so that it does not enter area 0?

Answer 22

area 0 filter-list prefix-list FILTRO_OSPF in

Question 23

How to filter OSPF routes so they do not enter the RIB?

Answer 23

router ospf 12, area 3 filter-list prefix DENY-OSPF in, ip prefix-list DENY-OSPF: 2 entries, seq 5 deny 12.0.255.23/32, seq 10 permit 0.0.0.0/0 le 32

Question 24

What are the possibilities for route filtering?

Answer 24

Summary of filtering possibilities: Filter type 3 LSAs in ABRs, Filter type 5 LSAs in ASBRs, Filter routes to be installed in the local routing table

Question 25

What metric will be assigned to a summarized route?

Answer 25

The best metric among the subordinate routes

Question 26

What are the ways to generate a default route in OSPF?

Answer 26

area range 0.0.0.0 0.0.0.0 or summary address (ASBRs), Command default-information originate

Question 27

Which type of special area does not receive a default route by default?

Answer 27

Not So Stub

Question 28

Which LSAs are allowed in a Stub area?

Answer 28

1, 2, and 3 + default route via 3

Question 29

Which LSAs are allowed in a Not So Stub Area?

Answer 29

1, 2, 3, and 7 (without default route)

Question 30

Which LSAs are allowed in a Totally Stub Area?

Answer 30

1, 2 + default route via 3

Question 31

Which LSAs are allowed in a Totally Not So Stub Area?

Answer 31

1, 2, and 7 + default route

Question 32

Consider the topology: R1 R2 R3 R4. How should the virtual link be configured?

Answer 32

In R2 create a virtual link to the RID of R3 and vice versa, the transit area 1 must be referenced, in OSPFv3 this is done the same way but within the IPv6 unicast address family

Question 33

In which network types does the next hop change occur?

Answer 33

In point-to-multipoint

Question 34

In which network types must hellos be sent via unicast?

Answer 34

All non-broadcast, but why?

Question 35

In which network types does the router announce the interface IP as /32?

Answer 35

In PMP and PMP NB and loopback

Question 36

What is the AD for a summarized route in an ASBR?

Answer 36

254

Question 37

What is the AD for a summarized route in an ABR?

Answer 37

110

Question 38

Area x filter-list prefix-list in or out. The above command applies to which type of LSA?

Answer 38

Type 3

Question 39

The filter list command in the in direction filters LSA entering the area

Answer 39

True

Question 40

The filter list command in the out direction filters LSA entering the area

Answer 40

False

Question 41

External routes are not filtered in ABRs due to the flooding scope of type 5 LSAs being the entire domain

Answer 41

True, filtering must be done in the ASBR