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CCNP Route

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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1. What OSPF-related command allows you to reset the refbw value used in the formula for OSPF cost calculation?
EIGRP uses the multicast IP address of 224.0.0.10 for Hellos and routing updates.
Local Preference - Atomic Aggregate
To reset the value - use the following command on each router: Router(config-router)# auto-cost reference-bandwidth refbw
Router# clear ip bgp ip-address soft out

2. Describe a typical form that your communities can take.
A site that has two connections to the same ISP - either from one router or two routers. One might be primary and the other backup - or the site might load balance over both links. Either static or dynamic routing would work in this case.
[AS-number]:[low-order-16-bits]
Link flapping - Network type being broadcast - PPP host route being redistributed - One router being not demand-circuit capable
Place a static route pointing to NULL0 in the IP routing table.

3. How often are Hello packets sent on a point-to-point subinterface in an EIGRP environment?
Use the neighbor [ip address] next-hop-self command in BGP configuration mode.
Hellos are sent every 5 seconds on broadcast links - as well as p2p serial - p2p subinterface - and multipoint circuits greater than T1.
A site with two connections to multiple ISPs. This gives the most redundancy. BGP is used with the ISPs and can be used internally also.
The next hop router for a backup path is called the feasible successor.

4. You are considering the usage of manual route summarization in your EIGRP network. How is the metric calculated for the summary route.
Local preference can be used to enact global autonomous system routing policies.
Route reflectors help address the fact that BGP requires that all BGP peers in the same autonomous system form an Internal BGP (IBGP) session with all peers in the autonomous system.
The minimum metric of the specific routes is used as the metric of the summary route.
The default origin code for BGP routes that you inject using redistribution is unknown.

5. What does BGP stand for?
Mismatched interface MTU - Duplicate router IDs on routers - Broken unicast connectivity - Network type of point-to-point between PRI and BRI/dialer
Hellos are sent every 5 seconds on broadcast links - as well as p2p serial - p2p subinterface - and multipoint circuits greater than T1.
A transit AS is an AS through which traffic to another AS travels - such as with an ISP.
Border Gateway Protocol

6. What is the command that you use in EIGRP to control the load balancing across unequal cost paths?
The command is applied on all routers in the area.
Use the variance command in EIGRP to control load balancing behavior[md]potentially across unequal bandwidth links.
The ASBR Summary (Type 4) LSA advertises an Autonomous System Boundary Router (ASBR) destination. This LSA is originated at an ABR. This LSA type is flooded throughout an autonomous system.
You can use the show ip ospf command to verify the router ID of an OSPF-speaking router.

7. To configure an OSPF area as Totally Stubby - which systems need to have the no-summary keyword configured?
The no-summary keyword needs to be used on the ABR only.
This regular expression matches routes that originated in autonomous system 200.
Origin - AS-Path - Next-Hop
Interior Gateway Protocol(IGP)

8. In a LAN - with which router(s) does a DROTHER form an adjacency?
DROTHERs form an adjacency with the DR and BDR.
Router(config-router)# neighbor ip-address route-map name in
The highest IP address of an active interface is selected; any loopback interface overrides this behavior. Therefore - if you have loopback interfaces - the highest IP address on an active loopback interface is selected.
A site that has two connections to the same ISP - either from one router or two routers. One might be primary and the other backup - or the site might load balance over both links. Either static or dynamic routing would work in this case.

9. Update
A transit AS is an AS through which traffic to another AS travels - such as with an ISP.
Message used to transfer routing information between peers. Includes new routes - withdrawn routes - and path attributes.
For the Broadcast Cisco mode of operation: Dynamic or manual neighbor configuration? Dynamic - DR/BDR election required? DR/BDR election
The correct command is show ip bgp.

10. Name at least two reasons that an OSPF neighbor can be stuck in the INIT state:
Using the default-metric command in BGP configuration mode causes all redistributed networks to have the specified MED value.
Access list or L2 problem blocking Hellos in one direction - Multicast non-functional on one side - Authentication configured on only one side - broadcast keyword missing from the map command
Cisco's implementation of OSPF calculates the metric using the following formula: - cost = refbw/bandwidth - The default refbw is 100 Mbps.
Place a static route pointing to NULL0 in the IP routing table.

11. What does a Type 2 LSA describe - what router produces it - and Where is it flooded?
The Network LSA (Type 2) lists all attached routers. These LSAs are produced by the DR on every multi-access network. They are flooded within the originating area.
The ASBR Summary (Type 4) LSA advertises an Autonomous System Boundary Router (ASBR) destination. This LSA is originated at an ABR. This LSA type is flooded throughout an autonomous system.
Multiply the IGRP metric by 256.
BGP peers exchange keepalive messages every 60 seconds by default. These keep the peering session active.

12. How many instances of BGP can be run on a single router?
The next hop router for a backup path is called the feasible successor.
On-demand circuit is an enhancement that allows efficient operations over dialup - ISDN - and other on-demand circuits.
Only one instance of BGP can be run on a single router
The Network LSA (Type 2) lists all attached routers. These LSAs are produced by the DR on every multi-access network. They are flooded within the originating area.

13. The metric of EIGRP is compatible with the metric of the earlier Interior Gateway Routing Protocol (IGRP). How do you convert the IGRP metric to the form of EIGRP?
The Private autonomous system number range is 64512[nd]65535.
Local preference can be used to enact global autonomous system routing policies.
Multiply the IGRP metric by 256.
A site with two connections to multiple ISPs. This gives the most redundancy. BGP is used with the ISPs and can be used internally also.

14. What is the correct router configuration command that must be issued on all routers in an OSPF area to use the strongest authentication method possible?
EIGRP uses IP protocol number 88.
This percentage can be changed on a per-interface basis by using the ip bandwidth-percent eigrp interface configuration command.
Router(config-router)# area area_id authentication message-digest Note: Additional (interface configuration) commands are required for the configuration of authentication - but this is the router configuration command required.
The default LSA aging timer is 30 minutes.

15. What are five possible reasons that the OSPF neighbor list might be empty when troubleshooting OSPF?
For the Point-to-point Cisco mode of operation: Dynamic or manual neighbor configuration? Dynamic DR/BDR election required? Not required
Link flapping - Network type being broadcast - PPP host route being redistributed - One router being not demand-circuit capable
OSPF not enabled properly on appropriate interfaces - Layer 1 or 2 not functional - Passive interface configured - Access list(s) blocking Hello packets in multiple directions - Error in IP address or subnet mask configuration - Hello or Dead interva
Hellos are sent every 5 seconds on broadcast links - as well as p2p serial - p2p subinterface - and multipoint circuits greater than T1.

16. By default - how much bandwidth does EIGRP consume on an interface for its operations?
Cisco's implementation of OSPF calculates the metric using the following formula: - cost = refbw/bandwidth - The default refbw is 100 Mbps.
You can configure manual manipulation of the AS-path attribute with the set as-path prepend command.
EIGRP uses up to 50 percent of the bandwidth (as set by the bandwidth command) for its operations.
The command is applied on all routers in the area.

17. You are concerned that a flapping route is ruining the stability of your BGP network. What command allows the router to remove the update until it is proven to be more stable?
The Network LSA (Type 2) lists all attached routers. These LSAs are produced by the DR on every multi-access network. They are flooded within the originating area.
The AS External (Type 5) LSAs advertise an external destination or a default route to an external destination. These LSAs are originated by ASBRs. They are flooded throughout the autonomous system.
ADD - Adds a line to a prefix-list filter on the remote peer - DELETE - Removes a line from a filter that was previously installed on a remote peer - DELETE ALL - Removes all previously installed filters on the remote peer
Route dampening can make the network more stable. To enable route dampening - use the bgp dampening command.

18. What command should you use to verify the router ID of an OSPF-speaking router?
You can use the show ip ospf command to verify the router ID of an OSPF-speaking router.
BGP peer groups would be ideal for this situation.
OSPF uses IP protocol number 89.
Router(config-router)# neighbor ip-address shutdown

19. How often are Hello packets sent on a multipoint circuit with bandwidth less than T1 in an EIGRP environment?
Hellos are sent every 60 seconds on multipoint circuits with bandwidth less than T1.
Local preference can be used to enact global autonomous system routing policies.
Aggregator - Community
In EIGRP - a reliability of value 1 indicates a completely unreliable link.

20. What does a Type 4 LSA describe - what router produces it - and Where is it flooded by default?
External BGP is a BGP peering relationship between routers in different autonomous systems.
The network backdoor router configuration command causes the administrative distance assigned to the network to be forced to 200. The goal is to make Interior Gateway Protocol (IGP) learned routes preferred.
For the Broadcast Cisco mode of operation: Dynamic or manual neighbor configuration? Dynamic - DR/BDR election required? DR/BDR election
The ASBR Summary (Type 4) LSA advertises an Autonomous System Boundary Router (ASBR) destination. This LSA is originated at an ABR. This LSA type is flooded throughout an autonomous system.

21. Keepalive
When a problem occurs that causes a router to end the BGP peering session - a notificationmessage is sent to the BGP neighbor and the connection is closed.
Hellos are sent every 5 seconds on broadcast links - as well as p2p serial - p2p subinterface - and multipoint circuits greater than T1.
OSPF addresses packets to multicast address 224.0.0.5.
BGP peers exchange keepalive messages every 60 seconds by default. These keep the peering session active.

22. What are two possible causes for an ABR not to advertise a summary route?
An ABR might not advertise a summary route for the following reasons:
DROTHERs form an adjacency with the DR and BDR.
The AD is the cost between that next hop router and the destination.
A list of networks known by BGP - along with their paths and attributes. To view it - use the show ip bgp command.

23. You need to suppress the periodic Hellos so that an ISDN link is not constantly enabled in a dial-on-demand routing (DDR) environment. What feature of OSPF should you use?
A list of paths to each network used by the router - and the next hop for each network. To view it - use the show ip route command.
A virtual link is a link to the backbone through a non-backbone area. Virtual links are created between two ABRs - and the area cannot be stub.
Router(config-router)# neighbor ip-address route-reflector-client
On-demand circuit is an enhancement that allows efficient operations over dialup - ISDN - and other on-demand circuits.

24. What is the correct command to configure a Not-So-Stubby Area in OSPF?
Lowest cost route calculated by adding the cost between the next hop router and the destination (AD) and the cost between the local router and the next hop. This sum is referred to as the FD.
The correct command to configure a Not-So-Stubby Area in OSPF is as follows: Router(config-router)# area area-id nssa [no-redistribution] [default-information-originate]
The only LSA flooded into the area is a single Type 3 default LSA.
Default routes from each provider - default routes plus some more specific routes - and all routes from all providers. Either use static routes - or advertise the site routes to the ISP and receive a default route from the ISP.

25. What are the three BGP route reception options?
The next hop router for a backup path is called the feasible successor.
A virtual link is a link to the backbone through a non-backbone area. Virtual links are created between two ABRs - and the area cannot be stub.
DROTHERs form an adjacency with the DR and BDR.
Default routes from each provider - default routes plus some more specific routes - and all routes from all providers. Either use static routes - or advertise the site routes to the ISP and receive a default route from the ISP.

26. For the nonbroadcast (NBMA) RFC-compliant mode of operation - fill in the following information: Dynamic or manual neighbor configuration? ________ DR/BDR election required?
For the nonbroadcast (NBMA) RFC-compliant mode of operation: Dynamic or manual neighbor configuration? Manual - DR/BDR election required? DR/BDR election
Use the following command to configure route summarization on an ASBR to summarize external routes: Router(config-router)# summary-address address mask [not-advertise] [tag tag]
On-demand circuit is an enhancement that allows efficient operations over dialup - ISDN - and other on-demand circuits.
Exterior Gateway Protocol(EGP). BGP v4 is the only EGP currently in use.

27. Name two Transitive BGP attributes.
In EIGRP - a reliability of value 1 indicates a completely unreliable link.
OSPF not enabled properly on appropriate interfaces - Layer 1 or 2 not functional - Passive interface configured - Access list(s) blocking Hello packets in multiple directions - Error in IP address or subnet mask configuration - Hello or Dead interva
The highest IP address of an active interface is selected; any loopback interface overrides this behavior. Therefore - if you have loopback interfaces - the highest IP address on an active loopback interface is selected.
Aggregator - Community

28. Describe BGP loop prevention.

29. You need to configure BGP community propagation for a large number of BGP neighbors. What is the ideal mechanism to use to assist with this configuration?
The router responds with an update of the routing information it possesses.
BGP peer groups would be ideal for this situation.
ADD - Adds a line to a prefix-list filter on the remote peer - DELETE - Removes a line from a filter that was previously installed on a remote peer - DELETE ALL - Removes all previously installed filters on the remote peer
Use the bgp default local-preference command to change the default local preference value applied to all updates coming from external neighbors or originating locally.

30. What is the effect of the network backdoor command in BGP?
The only LSA flooded into the area is a single Type 3 default LSA.
The network backdoor router configuration command causes the administrative distance assigned to the network to be forced to 200. The goal is to make Interior Gateway Protocol (IGP) learned routes preferred.
These are Type-2 external routes. Again - they define networks outside of the autonomous system and are advertised by Type 5 LSAs. In this case cost is always the external cost only. This is the default OSPF external route type on Cisco routers.
Multi Exit Discriminator.

31. What is the term for BGP neighbors?
Router(config-router)# neighbor ip-address route-map name in
Use the following command to configure route summarization on an ASBR to summarize external routes: Router(config-router)# summary-address address mask [not-advertise] [tag tag]
BGP peers
[AS-number]:[low-order-16-bits]

32. What is the Feasible Distance (FD) value in EIGRP?
This percentage can be changed on a per-interface basis by using the ip bandwidth-percent eigrp interface configuration command.
Lowest cost route calculated by adding the cost between the next hop router and the destination (AD) and the cost between the local router and the next hop. This sum is referred to as the FD.
OSPF uses IP protocol number 89.
The BGP process injects local routes in two different ways[md]1) using the network configuration commands and 2) using redistribution by another routing protocol.

33. What key design requirement of BGP does a BGP route reflector address?
Route reflectors help address the fact that BGP requires that all BGP peers in the same autonomous system form an Internal BGP (IBGP) session with all peers in the autonomous system.
A site with two connections to multiple ISPs. This gives the most redundancy. BGP is used with the ISPs and can be used internally also.
IP network numbers and subnet masks (prefix-list or access-list) - Route originator - Next hop - Origin code - Tag value attached to an Interior Gateway Protocol (IGP) route - AS-path - Community - IGP route type
Updates are sent to the DR.

34. What is the command to change the cost of the default route used within a Totally Stubby area?
Exterior Gateway Protocol(EGP). BGP v4 is the only EGP currently in use.
The neighbor command can be used to manually configure a neighbor in a NBMA OSPF environment. The full syntax of the command is: - Router(config-router)# neighbor ip-address [priority number] [poll-interval seconds] [cost number] [database-filter all
Router(config-router)# area area-id default-cost cost
Type 7 LSAs are special external routes that you permit in a Not-So-Stubby area.

35. You have local BGP routing policies you can enact - and you have global autonomous system policies that you can implement. What is the purpose of local preference - local or global?
Local preference can be used to enact global autonomous system routing policies.
The default cost of the default route is 1.
Place a static route pointing to NULL0 in the IP routing table.
200

36. When a BGP router receives an update from an EBGP neighbor - it must pass that update to its IBGP neighbors without changing the next-hop attribute. Therefore - IBGP routers must have a route to the network connecting their autonomous system to that
Exterior Gateway Protocol(EGP). BGP v4 is the only EGP currently in use.
Use the neighbor [ip address] next-hop-self command in BGP configuration mode.
The default cost of the default route is 1.
Link flapping - Network type being broadcast - PPP host route being redistributed - One router being not demand-circuit capable

37. Once adjacencies are established in the LAN and router information is being maintained - what step follows a router noticing a change and multicasting an LSU to 224.0.0.6?
External BGP is a BGP peering relationship between routers in different autonomous systems.
This percentage can be changed on a per-interface basis by using the ip bandwidth-percent eigrp interface configuration command.
The next step in the update process features the DR acknowledging the LSU and flooding it to all OSPF speakers using multicast 224.0.0.5.
For an OSPF router to advertise a default route into an area - the command default-information originate must be used. If the advertising router does not possess a default route in its routing table - you can use the always keyword to still generate

38. What is the meaning of the following regular expression: _200$
For the Point-to-multipoint RFC-compliant mode of operation: Dynamic or manual neighbor configuration? Dynamic DR/BDR election required? Not required
Router# clear ip bgp ip-address soft out
This regular expression matches routes that originated in autonomous system 200.
ADD - Adds a line to a prefix-list filter on the remote peer - DELETE - Removes a line from a filter that was previously installed on a remote peer - DELETE ALL - Removes all previously installed filters on the remote peer

39. Describe an autonomous system(AS).
Packets that require acknowledgement are as follows: Update - Query - Reply
The next hop router for a backup path is called the feasible successor.
An autonomous system is a group of networks under a common administration. The Internet Assigned Numbers Authority(IANA) assigns AS numbers: 1 to 64511 are public AS numbers and 64512 to 65535 are private AS numbers.
The default value of the MED attribute is 0.

40. You have configured the demand-circuit configuration in your OSPF network - but the link keeps coming up because of OSPF. Name at least three possible reasons for this.
BGP communicates over TCP port 179
A list of paths to each network used by the router - and the next hop for each network. To view it - use the show ip route command.
Link flapping - Network type being broadcast - PPP host route being redistributed - One router being not demand-circuit capable
Confederations are another method of solving the IBGP full mesh requirement. Confederations are smaller sub-autonomous systems created within the primary autonomous system to decrease the number of BGP peer connections.

41. Another method is commonly used to solve the IBGP full mesh requirement. It involves the configuration of smaller sub-autonomous systems created within a primary autonomous system. What are these called?
OSPF addresses packets to multicast address 224.0.0.5.
Exterior Gateway Protocol(EGP). BGP v4 is the only EGP currently in use.
Packets that require acknowledgement are as follows: Update - Query - Reply
Confederations are another method of solving the IBGP full mesh requirement. Confederations are smaller sub-autonomous systems created within the primary autonomous system to decrease the number of BGP peer connections.

42. What is the term for routers running BGP?
This percentage can be changed on a per-interface basis by using the ip bandwidth-percent eigrp interface configuration command.
Place a static route pointing to NULL0 in the IP routing table.
BGP speakers
Access list or L2 problem blocking Hellos in one direction - Multicast non-functional on one side - Authentication configured on only one side - broadcast keyword missing from the map command

43. Name at least one reason that an OSPF neighbor can be stuck in the ATTEMPT state.
Hellos are sent every 5 seconds on broadcast links - as well as p2p serial - p2p subinterface - and multipoint circuits greater than T1.
Route tagging with communities is always done with a route map. You can specify any number of communities. Communities specified in the set keyword overwrite existing communities unless you specify the additive option.
Misconfigured neighbor statement - Unicast non-functional in NBMA environment
Mismatched MTU - Corrupted link-state request packet

44. You need to change the default local preference value applied to all updates coming from external neighbors or originating locally. What command should you use?
Use the bgp default local-preference command to change the default local preference value applied to all updates coming from external neighbors or originating locally.
BGP speakers
You must manipulate the K values on all routers if you plan to manipulate them on one.
A list of all configured BGP neighbors. To view it - use the show ip bgp summary command.

45. To what IP address does OSPF send packets destined for the Designated Router (DR) and Backup Designated Router (BDR) in the LAN?
OSPF addresses packets to multicast address 224.0.0.6.
Router# clear ip bgp ip-address soft out
The NSSA External (Type 7) LSA is almost identical to a Type 5 AS External LSA - yet it is used to create Not-So-Stubby Areas. An NSSA ASBR generates this LSA - and an NSSA ABR translates it into a Type 5 LSA - which gets propagated into the OSPF dom
The Cisco mode of Broadcast requires a full mesh topology.

46. Describe a dual-multihomed network.
A site with two connections to multiple ISPs. This gives the most redundancy. BGP is used with the ISPs and can be used internally also.
OSPF addresses packets to multicast address 224.0.0.5.
Using the default-metric command in BGP configuration mode causes all redistributed networks to have the specified MED value.
Updates are sent to the DR.

47. What kind of routing protocol is BGP?
The only LSA flooded into the area is a single Type 3 default LSA.
BGP is a path-vector protocol
Hellos are sent every 60 seconds on multipoint circuits with bandwidth less than T1.
You can configure manual manipulation of the AS-path attribute with the set as-path prepend command.

48. Which of the Cisco OSPF nonbroadcast multiaccess (NBMA) modes of operation requires a full mesh topology?
The command is applied on all routers in the area.
The Cisco mode of Broadcast requires a full mesh topology.
Local preference can be used to enact global autonomous system routing policies.
A site with two connections to multiple ISPs. This gives the most redundancy. BGP is used with the ISPs and can be used internally also.

49. You can manipulate the administrative distance of three different types of OSPF routes. What are the three types?
A site connected to more than one ISP at the same time. It is done for redundancy and backup if one ISP fails - and for better performance if one ISP provides a better path to frequently used networks. This also gives you an ISP-independent solution.
No DR/BDR election exists in a point-to-point environment by default.
Three different administrative distance values are possible for OSPF[md]intra-area routes - inter-area routes - and external routes. By default all are set to 110.
The default origin code for BGP routes that you inject using redistribution is unknown.

50. In a Not-So-Stubby Area - what router translates the Type 7 LSA - and What is the LSA translated into?
The Type 7 LSA is translated into a Type 5 LSA by the ABR.
Message used to transfer routing information between peers. Includes new routes - withdrawn routes - and path attributes.
Three different administrative distance values are possible for OSPF[md]intra-area routes - inter-area routes - and external routes. By default all are set to 110.
An autonomous system is a group of networks under a common administration. The Internet Assigned Numbers Authority(IANA) assigns AS numbers: 1 to 64511 are public AS numbers and 64512 to 65535 are private AS numbers.