1 - Cisco Icnd2 - Ospf And Rip

Front 1

OSPF: 3 major categories of data and corresponding show commands

Back 1

1. Neighbors (show ip ospf neighbor)
2. Database (show ip ospf database)
3. Route calculation (sho ip route)

Front 2

OSPF: To what IP address does OSPF send Hello messages?

Back 2

Multicast 224.0.0.5

Front 3

OSPF: Default hello interval and dead interval

Back 3

1. Hello interval = 10 seconds
2. Dead interval = 4 * hello or 40 seconds

Front 4

OSPF: What must match in hello messages to become neighbors (4 items)?

Back 4

1. Subnet number and mask
2. hello and dead intervals
3. OSPF area ID
4. Authentication (if used)

Front 5

OSPF: What are the 5 neighbor states?

Back 5

1. Down - previously known neighbor, but interface failed
2. Init - hellos exchanged
3.Seen - config details matched
4. two-way: state for non-adjacent routers
5. Full: database exchange completed

Front 6

OSPF: What is a designated router (DR) and backup (BDR)?

Back 6

Designated router (DR) is used on a broadcast LAN subnet to reduce the number relationships required. BDR functions as a backup DR. All other routers try to form neighbor relationships with the DR and the BDR.

Front 7

OSPF: What type of interface requires a designated router?

Back 7

Broadcast interface type requires a DR
Point to point does not require a DR.

Front 8

OSPF: How are DR and BDR selected?

Back 8

Router with highest OSPF priority wins election as DR
highest router id is tiebreaker.

Front 9

OSPF: How to determine router id?

Back 9

1. Configure using subcommand #router-id
2. Use highest IP address of loopback interface in up/up state
3. Use highest IP address of any interface in up/up state.

Front 10

OSPF: What is the routing algorithm?

Back 10

The Dijkstra Shortest Path First algorithm

Front 11

OSPF: What is an area border router (ABR)?

Back 11

Any router that is connected to the backbone area and at least one other area.

Front 12

OSPF: What is the backbone area?

Back 12

Area 0
A specifal OSPF area to which all other ares must connect.

Front 13

OSPF: What is a backbone router?

Back 13

Any router in the backbone area (area 0).

Front 14

OSPF: What is an internal router?

Back 14

Any router in a single non-backbone area.

Front 15

OSPF: What is an autonomous system border router(ASBR)?

Back 15

A router that connects to routers that do not use OSPF. Exchanges routes.

Front 16

OSPF: List 3 OSPF route types

Back 16

1. Intra-area route: route to subnet in same area.
2. Inter-area route: route to subnet in different area
3. External route: route to subnet outside the OSPF domain and advertised into the domain.

Front 17

OSPF: CLI commands to configure OSPF

Back 17

1. #router ospf <process id>
2. #Router-id <value>
3. #network <network-addr><inverse mask> area <area-number>

Front 18

OSPF: CLI commands to configure a loopback interface

Back 18

1. #interface loopback <n>
2. #ip address <ip-addr> <mask>

Front 19

OSPF: CLI mode and commands to set hello-timer, dead-timer

Back 19

interface mode: 1. #ip ospf hello-interval <time>
2. #ip ospf dead-interval <time>

Front 20

OSPF: CLI mode and commands to set OSPF cost, bandwidth on interface

Back 20

interface mode:
#ip ospf cost <value>
#bandwidth <x> (in Kb)

Front 21

OSPF: CLI command to set auto-cost reference bandwidth.

Back 21

global: #auto-cost reference-bandwidth <value>
Units are M
Default is 100 M

Front 22

OSPF: CLI commands to configure OSPF to use authentication

Back 22

1. #router ospf <process id>
2. #area <n> authentication message-digest
if you leave off the "message-digest" keyword, it will do clear-text authentication

Front 23

OSPF: CLI commands to configure authentication on an interface

Back 23

1. #interface <type-number>
2. #ip ospf authentication
3. #ospf authentication message-digest
4. #osf message-digest-key 1 md5 <password>

Front 24

OSPF: CLI commands to display database, processes, neighbors

Back 24

1. #show ip ospf database
2. #show ip ospf
3. #show ip ospf neighbor

Front 25

OSPF: CLI command to show interfaces used by OSPF

Back 25

#show ip ospf interfaces brief

Front 26

OSPF: CLI commands to set interfaces to passive/not passive

Back 26

1. #passive interface <type number>
2. #no passive interface <type number>
3. #default passive interface (sets all interfaces to passive)

Front 27

OSPF: How are route metrics calculated?

Back 27

The route metric is the sum of the cost for each outgoing interface

Front 28

OSPF: How are costs for each interface calculated

Back 28

1. explicitly set with interface command: #ip ospf cost <value: 1-65,536>
2. Calculated as (reference bandwidth) / (interface bandwidth)

Front 29

OSPF: Default reference bandwidth and CLI command to change it

Back 29

1. Default is 100Mbps
2. #auto-cost reference-bandwidth <number> (units of Mbps)

Front 30

OSPF: What is the IOS command to remove the redistribution based on OSFP routing process ID?

Back 30

#clear ip ospf {pid}

Front 31

OSPF: What is the IOS command to view OSFP link-state advertisements requested by the router?

Back 31

#sho ip ospf request-list

Front 32

OSPF: What is the IOS command to view the OSPF routing tables entries to an ABR and ASBR?

Back 32

#sho ip ospf border-routers

Front 33

OSPF: IOS command to configure authentication type for an interface

Back 33

#ip ospf authentication

Front 34

OSPF: What is the default interface configuration used by OSPF to run over frame relay?

Back 34

Non-broadcast multi-access

Front 35

RIP: Attributes of a distance vector routing protocol

Back 35

1. Send full routing updates periodically
2. Routes should remain "young" (timer in routing table)
3. Full update limited by split-horizon rules

Front 36

RIP: Name 5 techniques used with distance vector protocols to prevent loops and count-to-infinity problems

Back 36

1. Route poisoning
2. Split horizon
3. Poisoned reverse
4. Tiggered updates
5. Holddown timers

Front 37

RIP: Describe route poisoning

Back 37

Used with distance vector protocols
advertise down routes as having infinite cost
deals with count-to-infinity problem

Front 38

RIP: Describe split horizon

Back 38

In routing updates sent out interface X, don't include routing information about routes that use X as the outgoing interface
prevents looping
prevents count-to-infinity

Front 39

RIP: Describe poison-reverse

Back 39

When learning of a failed route, suspend split-horizon rules and advertise a poisoned route

Front 40

RIP: Describe triggered updates

Back 40

When a route fails, do not wait for the next periodic update. Send out a triggered partial update listing the poisoned route.

Front 41

RIP: Describe the holddown timer

Back 41

As soon as a route is known to be down, hold it down for a time to give all routers time to learn of the failed route

Front 42

OSPF: Link State protocol attributes

Back 42

1. Link-state database on every router
2. starts by flooding network topology
3. refloods periodically (OSPF - 30 min. default)
4. Sends link-state advertisements (LSAs)

Front 43

OSPF and RIP: Compare Link State and Distance Vector routing protocols.

Back 43

1. Link state has much faster convergence
2. Link state requres more CPU and memory
3. Link state inherently avoids loops

Front 44

OSPF: IOS command to display hello timer settings

Back 44

#show ip ospf interfaces