CCNP 642-901 BSCI - Building Scalable Cisco Internetworks Version 01.17.08 Part-3

QUESTION 26:

EIGRP is being configured on the Certkiller network. After the initial configuration,
the EIGRP routers form relationships with its peer routers. Which three of the
following statements correctly describe these peer relationships? (Select three)
A. EIGRP will form neighbors if the routers are not adjacent
B. EIGRP will not form neighbors if the metric K-values do not match.
C. EIGRP will not form neighbors if the router AS numbers do not match.
D. EIGRP will form neighbors over primary and secondary interface addressing.
E. EIGRP will form neighbors even though hello and hold timers do not match on the
peering interfaces.


Answer: B, C, E
Explanation:
B: To become neighbors the routers metric must be comparable.
C: EIGRP neighbors must have the same AS number.
E: It is possible for two routers to become EIGRP neighbors even though the hello and
hold timers don't match.
Incorrect Answers:
A: Neighbor discovery/recovery is the process that routers use to dynamically learn of
other routers on their directly attached networks.
D: EIGRP doesn't build peer relationships over secondary addresses.
Reference: Cisco White Paper, Enhanced Interior Gateway Routing Protocol
http://www.cisco.com/warp/public/103/eigrp1.html

QUESTION 27:
The Certkiller network is an EIGRP network consisting of four links (Link A, Link
B, Link C, & Link D). The costs associated with each link is A=1, B=3, C=2, D=4.
According to the variables below, which link is going to be the feasible successor?
A. Link A
B. Link B
C. Link C
D. Link D

Answer: C
Explanation:
Link A is the best link and it therefore the successor. Link C is the next best link, and it is
therefore the feasible successor.
Incorrect Answers
A: Link A is the successor, not the feasible successor.
B: Both Link A and Link C are better than Link B.
D: The feasible successor must have Advertised Destination that is less than the Feasible
Distance.
Note: Feasible distance is the best metric along a path to a destination network, including
the metric to the neighbor advertising that path. Reported distance, or advertised distance,
is the total metric along a path to a destination network as advertised by an upstream
neighbor. A feasible successor is a path whose reported distance is less than the feasible
distance.
Reference: Enhanced Interior Gateway Routing Protocol
http://www.cisco.com/warp/public/103/eigrp1.html

QUESTION 28:
Part of the routing table of router CK1 is displayed below:
S 62.99.153.0/24 [1/0] via 209.177.64.130
172.209.12.0/32 is subnetted, 1 subnets
D EX 172.209.1
[170/2590720] via 209.179.2.114, 06:47:28, Serial0/0/0.1239
62.113.17.0/24 is variably subnetted, 2 subnets, 2 masks
D EX 99.3.215.0/24
[170/27316] via 209.180.96.45, 09:52:10, FastEthernet11/0/0
[170/27316] via 209.180.96.44, 09:52:10, FastEthernet11/0/0
25.248.17.0/24
[90/1512111] via 209.179.66.25, 10:33:13, Serial0/0/0.1400001
[90/1512111] via 209.179.66.41, 10:33:13, Serial0/0/0.1402001
62.113.1.0/24 is variably subnetted, 12 subnets, 2 masks
D 62.113.1.227/32
[90/2611727] via 209.180.96.45, 10:33:13, FastEthernet1/0/0
[90/2611727] via 209.180.96.44, 10:33:13, FastEthernet1/0/0
S* 0.0.0.0/0 [1/0] via 209.180.96.14
From analyzing the above command output, what is the administrative distance of
the external EIGRP routes?
A. 24
B. 32
C. 90
D. 170
E. 27316
F. None of the above
Answer: D
Explanation:
By default an external EIGRP route has a value of 170. By examining the exhibit we see
that this default value of the external EIGRP routes (see D-EX in exhibit) indeed is set to
170. The first value within the brackets display the AD, so with a value of [170/27316]
the AD is 170 and the metric of the route is 27316.
Incorrect Answers:
A, B: This is the subnet mask used for some of the routes in the table.
C: This is the AD of the internal EIGRP routes, which is the default
E: This is the EIGRP metric of the external EIGRP routes.
Reference: What Is Administrative Distance?
http://www.cisco.com/warp/public/105/admin_distance.html

QUESTION 29:


The Certkiller network is shown below, along with the relevant router
configurations:
CK1 # show run
interface Loopback0
ip address 10.10.10.1 255.255.255.0
!
interface Ethernet0
ip address 172.29.1.1 255.255.255.0
media-type 10BaseT
!!
router eigrp 100
redistribute connected
network 172.29.0.0
auto-summary
no eigrp log-neighgbor-changes
!
ip classless
no ip http server
CK2 # show run
interface Ethernet0
ip address 172.29.1.2 255.255.255.0
media-type 10BaseT
!
interface Ethernet1
ip address 172.19.2.2 255.255.255.0
media-type 10BaseT!
router eigrp 100
network 172.19.0.0
network 172.29.0.0
!
ip classless
no ip http server
CK3 # show run
interface Ethernet1/0
ip address 172.19.2.3 255.255.255.0
!
router eigrp 100
network 172.19.0.0
auto-summary
no eigrp log-neighbor-changes
!
ip classless
ip http server
With the topology found in the graphic, what will the CK1 loopback 0 be in the CK3
routing table?
A. It will show up in the routing table as D 10.0.0/8.
B. It will show up in the routing table as D EX 10.0.0.0/8.
C. It will show up in the routing table as D 10.0.0./24.
D. It will not show up in CK3 routing table because there is no network command on
CK1 .

Answer: B
Explanation:
Because router CK1 is configured with route redistribution, it will redistribute the
connected loopback network into EIGRP. Because redistributed routes will show up as
external EIGRP routes in the routing table, choice B is correct. Although the loopback
interface is using a /24 subnet mask, EIGRP summarizes at network boundaries by
default so the network will appear as the class A network of 10.0.0.0/8 in the routing
table of the other routers.
Incorrect Answers:
A: The route will be external, since it was redistributed into EIGRP.
C: It will be external because of redistribution, and it will also be summarized since that
is the default behavior of EIGRP.
D: Although it was not configured under the EIGRP network command, it would be
redistributed because it is a connected route.

QUESTION 30:
EIGRP has been configured as the routing protocol on the Certkiller network.
Which statements are true regarding EIGRP? (Choose three)
A. By default, EIGRP performs auto-summarization across classful network boundaries.
B. EIGRP uses an area hierarchy to increase network scalability
C. To speed convergence, EIGRP attempts to maintain a successor and feasible successor
path for each destination.
D. EIGRP uses hellos to establish neighbor relationships.
E. By default, EIGRP uses the Dijkstra algorithm to determine the best path to
destination network based on bandwidth and delay.
Answer: A, C, D
Explanation:
The default behavior of EIGRP routers is to automatically summarize routes at the
network boundary.
EIGRP routers maintain information regarding the successors and the feasible successors
to each network destination. This information is useful in the convergence time whenever any of the links fail.
EIGRP neighbors periodically use hellos to establish the relationship. Should any of the neighbors fail, triggered updates are sent to update the network regarding the topology
change.
Incorrect Answers:
B: EIGRP networks are inherently flat, as each router is perceived as a peer to every
other EIGRP router. IS-IS and OSPF utilize hierarchical network topologies.
E: The Dijkstra algorithm is used by link state routing protocols. EIGRP is considered to
be a hybrid routing protocol.

QUESTION 31:
Router Certkiller 1 is the headquarters router in a hub and spoke topology supporting 24 remote offices. Point-to-multipoint Frame Relay EIGRP network is deployed between the headquarters and the remote offices. There is no bandwidth command configured under either the major serial interface or the subinterface on router Certkiller
1. What is the bandwidth of each Frame Relay connection perceived
by the EIGRP process?
A. 64 kbps
B. 128 kbps
C. 1.544 Mbps
D. 1.536 Mbps

Answer: A
Explanation:
The default behavior of EIGRP routers is to automatically summarize routes at the
network boundary.
EIGRP routers maintain information regarding the successors and the feasible successors
to each network destination. This information is useful in the convergence time whenever
any of the links fail.
EIGRP neighbors periodically use hellos to establish the relationship. Should any of the neighbors fail, triggered updates are sent to update the network regarding the topology
change.
Incorrect Answers:
B: EIGRP networks are inherently flat, as each router is perceived as a peer to every
other EIGRP router. IS-IS and OSPF utilize hierarchical network topologies.
E: The Dijkstra algorithm is used by link state routing protocols. EIGRP is considered to be a hybrid routing protocol

QUESTION 31:
Router Certkiller 1 is the headquarters router in a hub and spoke topology
supporting 24 remote offices. Point-to-multipoint Frame Relay EIGRP network is
deployed between the headquarters and the remote offices. There is no bandwidth
command configured under either the major serial interface or the subinterface on
router Certkiller 1. What is the bandwidth of each Frame Relay connection perceived
by the EIGRP process?
A. 64 kbps
B. 128 kbps
C. 1.544 Mbps
D. 1.536 Mbps
Answer: A
Explanation:
By default in point-to-multipoint Frame Relay EIGRP network all subinterfaces share the
642-901
Actualtests.com - The Power of Knowing
bandwidth and each one receives (throughput of the channel)/(number of subinterfaces)
throughput. In this case, the formula is 1544kbps/24 =64kbps.
QUESTION 32:
What administrative distance is given to EIGRP summary routes?
A. 0
B. 1
C. 5
D. 90
E. 95
F. 170
Answer: C
Explanation:
Default administrative Distance



QUESTION 33:
Which of the following statements are true about EIGRP operation? (Choose three)
A. When summarization is configured, the router will add a route to null 0
B. The summary route remains in the route table, even if there are no more specific
routes to the network.
C. Summarization is configured on a per-interface level.
D. The maximum metric for the specific routes is used as the metric for the summary
route.
E. Automatic summarization across major network boundaries is enabled by default.

Answer: A, C, E

Explanation:
Using the ip summary-address eigrp summarization command will causes the creation of
an EIGRP summary default route to the null0 interface with an administrative distance of
5. Caution should be taken when using this as a default route. The low administrative
distance of this default route can cause this route to displace default routes learned from
other neighbors from the routing table. If the default route learned from the neighbors is
displaced by the summary default route, or if the summary route is the only default route
present, all traffic destined for the default route will not leave the router, instead, this
traffic will be sent to the null0 interface where it is dropped.
By default, Cisco routers will automatically summarize EIGRP routes across major
network boundaries. With EIGRP, You can configure a summary aggregate address for a
specified interface. If there are any more specific routes in the routing table, EIGRP will
advertise the summary address out the interface with a metric equal to the minimum of all
more specific routes.
Incorrect Answers:
B: When all of the specific routes used within a summary route are deleted from the
routing table, the summary route will also be deleted.
D: The metric used in a summary route is the best metric from among the summarized
routes, not the maximum (worst).

QUESTION 34:
What action does an EIGRP router take when it cannot find a feasible successor for
a network?
A. It examines the routing and neighbor tables for the next best path.
B. It transitions from passive to active state for that network and queries its neighbors.
C. It examines the topology for a next best path.
D. It transitions from active to passive state for the next network and queries its
neighbors.

Answer: B
Explanation:
With EIGRP, A topology table entry for a destination can have one of two states. A route
is considered in the Passive state when a router is not performing a route recomputation.
The route is in Active state when a router is undergoing a route recomputation. If there
are always feasible successors, a route never has to go into Active state and avoids aroute recomputation.
When there are no feasible successors, a route goes into Active state and a route
recomputation occurs. A route recomputation commences with a router sending a query
packet to all neighbors. Neighboring routers can either reply if they have feasible
successors for the destination or optionally return a query indicating that they are
performing a route recomputation. While in Active state, a router cannot change the
next-hop neighbor it is using to forward packets. Once all replies are received for a given query, the destination can transition to Passive state and a new successor can be selected.


QUESTION 35:
The Certkiller EIGRP network is displayed in the following topology diagram:
You work as a network technician at Certkiller .com. Study the exhibits carefully. If
the command "variance 3" was added to the EIGRP configuration of Certkiller 5,
which path or paths would be chosen to route traffic from Certkiller 5 to network X?
A. Certkiller 5- Certkiller 2- Certkiller 1
B. Certkiller 5- Certkiller 2- Certkiller 1 and Certkiller 5- Certkiller 3- Certkiller 1.
C. Certkiller 5- Certkiller 3- Certkiller 1 and Certkiller 5- Certkiller 4- Certkiller 1.
D. Certkiller 5- Certkiller 2- Certkiller 1, Certkiller 5- Certkiller 3- Certkiller 1, and
Certkiller 5- Certkiller 4- Certkiller 1.

Answer: B
Explanation:
Every routing protocol supports equal cost path load balancing. In addition, Interior
Gateway Routing Protocol (IGRP) and EIGRP also support unequal cost path load
balancing. Use the variance n command in order to instruct the router to include
routes with a metric of less than n times the minimum metric route for that
destination. The variable n can take a value between 1 and 128. The default is 1, which means equal cost load balancing. Traffic is also distributed among the links with unequal costs, proportionately, with respect to the metric.
In this question the variance 3 command is used. In this instance, Certkiller 5 can get to Net X using the path CK5 - CK3 = metric of 10, and CK3 - CK3 = 10 as well with the FD between CK5 - CK1 being 10 + 10 = 20. Therefore, we can load balance on any route that had an FD of 3x the successor, or 3x20, which is 60
Important Note:If a path is not a feasible successor, the path is not used in load
balancing. This is why chose D is wrong as this path has an Advertised Distance of 25
which is greater than the successors FD. The link below refers to an example that is
nearly identical to the example in this question, except theirs used a variance of 2 and this question used a variance of 3.

Reference:
http://www.cisco.com/en/US/tech/ CK3 65/technologies_tech_note09186a008009437d.shtml

QUESTION 36:
What is the purpose of the "eigrp stub" configuration command?
A. To increase scalability by limiting the EIGRP query range.
B. To reduce the size of the routing table by blocking the D EX (External EIGRP) routes
in the EIGRP stub router.
C. To reduce the convergence time by enabling the EIGRP stub router to propagate the
EIGRP queries from the EIGRP hub router.
D. To reduce the convergence time by enabling the EIGRP stub router to also perform
query requests to the EIGRP hub router.

Answer: A
Explanation:
Complex, redundant EIGRP networks can cause scalability problems. The best solution
to this is to provide a means within the context of the EIGRP protocol itself to control traffic flows and limit query depth. TheEIGRP Stub Router functionality in Cisco IOS Software Release 12.0(7)T can achieve this solution.
The Enhanced Interior Gateway Routing Protocol (EIGRP) Stub Routing feature
improves network stability, reduces resource utilization, and simplifies stub router
configuration.
Stub routing is commonly used in a hub and spoke network topology. In a hub and spoke
network, one or more end (stub) networks are connected to a remote router (the spoke)
that is connected to one or more distribution routers (the hub). The remote router is
adjacent only to one or more distribution routers. The only route for IP traffic to follow into the remote router is through a distribution router. This type of configuration is
commonly used in WAN topologies where the distribution router is directly connected to a WAN. The distribution router can be connected to many more remote routers. Often, the distribution router will be connected to 100 or more remote routers. In a hub and spoke topology, the remote router must forward all non local traffic to a distribution router, so it becomes unnecessary for the remote router to hold a complete routing table. Generally, the distribution router need not send anything more than a default route to the remote router.
When using the EIGRP Stub Routing feature, you need to configure the distribution and
remote routers to use EIGRP, and to configure only the remote router as a stub. Only
specified routes are propagated from the remote (stub) router. The router responds to
queries for summaries, connected routes, redistributed static routes, external routes, and internal routes with the message "inaccessible." A router that is configured as a stub will send a special peer information packet to all neighboring routers to report its status as a stub router.
Any neighbor that receives a packet informing it of the stub status will not query the stubrouter for any routes, and a router that has a stub peer will not query that peer. The stub router will depend on the distribution router to send the proper updates to all peers.
Reference:
http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/products_feature_guide09186a0080087026.html

QUESTION 37:
The Certkiller network administrator has issued the "EIGRP stub" command on
router CK8 . What is the purpose of the "EIGRP stub" configuration command?
A. to reduce the convergence time by enabling the EIGRP stub router to propagate the
EIGRP queries from the EIGRP hub router.
B. to increase scalability by limiting the EIGRP query range.
C. to reduce the size of the routing table by blocking the D EX (External EIGRP) routes
into the EIGRP stub router.
D. to reduce the convergence time by enabling the EIGRP stub router to also perform
query requests to the EIGRP hub router.
E. None of the above.

Answer: B
Explanation:
The Enhanced Interior Gateway Routing Protocol (EIGRP) Stub Routing feature
improves network stability, reduces resource utilization, and simplifies stub router
configuration.
Stub routing is commonly used in a hub and spoke network topology. In a hub and spoke
network, one or more end (stub) networks are connected to a remote router (the spoke)
that is connected to one or more distribution routers (the hub). The remote router is
adjacent only to one or more distribution routers. The only route for IP traffic to follow into the remote router is through a distribution router. This type of configuration is commonly used in WAN topologies where the distribution router is directly connected to a WAN. The distribution router can be connected to many more remote routers. Often, the distribution router will be connected to 100 or more remote routers. In a hub and spoke topology, the remote router must forward all nonlocal traffic to a distribution router, so it becomes unnecessary for the remote router to hold a complete routing table.
Generally, the distribution router need not send anything more than a default route to the remote router.
When using the EIGRP Stub Routing feature, you need to configure the distribution and
remote routers to use EIGRP, and to configure only the remote router as a stub. Only
specified routes are propagated from the remote (stub) router. The router responds to
queries for summaries, connected routes, redistributed static routes, external routes, and internal routes with the message "inaccessible." A router that is configured as a stub will send a special peer information packet to all neighboring routers to report its status as a stub router.

Any neighbor that receives a packet informing it of the stub status will not query the stub router for any routes, and a router that has a stub peer will not query that peer. The stub router will depend on the distribution router to send the proper updates to all peers.
Router(config-router)# eigrp stub [receive-only | connected | static |summary]
:Configures a remote router as an EIGRP stub router.

QUESTION 38:
Router CK1 is an EIGRP router terminating a low speed circuit. When configuring
EIGRP to run across a 56 Kbps serial PPP link, what command do you need to put
under the serial interface to ensure proper convergence of EIGRP routes?
A. bandwidth 56000
B. bandwidth 56
C. ip bandwidth-percent eigrp 1 56
D. ip bandwidth-percent eigrp 1 56000
E. None of the above
Answer: B
Explanation:
When configuring serial links using EIGRP it is important to configure the bandwidth
setting on the interface. If the bandwidth setting is not changed for these interfaces EIGRP assumes the default bandwidth on the link instead of the true bandwidth. If the link is slower, the router may not be able to converge, routing updates might become lost,
or suboptimal path selection may result.
Router(config-if)#bandwidth kilobits
The value, kilobits, indicates the intended bandwidth in kilobits per second. For generic serial interfaces, such as PPP or HDLC, set the bandwidth to the line speed.


QUESTION 39:
Router CK1 is configured as shown below:
router eigrp 100
network 10.0.0.0
eigrp stub
Based on the information shown above, which two types of routes will be
advertised? (Select two)
A. Receive-only
B. Stub
C. Static
D. Summary
E. Connected
F. Dynamic


Answer: D, E
Explanation:
The Enhanced Interior Gateway Routing Protocol (EIGRP) Stub Routing feature
improves network stability, reduces resource utilization, and simplifies stub router
configuration.
Stub routing is commonly used in a hub and spoke network topology. In a hub and spoke
network, one or more end (stub) networks are connected to a remote router (the spoke)
that is connected to one or more distribution routers (the hub). The remote router is
adjacent only to one or more distribution routers. The only route for IP traffic to follow
into the remote router is through a distribution router. This type of configuration is
commonly used in WAN topologies where the distribution router is directly connected to
a WAN. The distribution router can be connected to many more remote routers. Often,
the distribution router will be connected to 100 or more remote routers. In a hub and
spoke topology, the remote router must forward all nonlocal traffic to a distribution
router, so it becomes unnecessary for the remote router to hold a complete routing table.
Generally, the distribution router need not send anything more than a default route to the remote router.
When using the EIGRP Stub Routing feature, you need to configure the distribution and
remote routers to use EIGRP, and to configure only the remote router as a stub. Only
specified routes are propagated from the remote (stub) router. The router responds to
queries for summaries, connected routes, redistributed static routes, external routes, and internal routes with the message "inaccessible." A router that is configured as a stub will send a special peer information packet to all neighboring routers to report its status as a stub router.
Any neighbor that receives a packet informing it of the stub status will not query the stub router for any routes, and a router that has a stub peer will not query that peer. The stub router will depend on the distribution router to send the proper updates to all peers.

:Configures a remote router as an EIGRP stub router.

QUESTION 40:
You need to configure EIGRP on a new Certkiller router. Which command should
you issue first to configure EIGRP for IP?
A. router eigrp autonomous-system-number
B. ip eigrp autonomous-system-number
C. ip eigrp routing
D. router eigrp process-id
E. None of the above
Answer: A
Explanation:
Despite the complexity of DUAL, configuring EIGRP can be relatively simple. EIGRP

configuration commands vary depending on the protocol that is to be routed. An example is IP, IPX, or AppleTalk. This section covers configuration commands for each of these routed protocols, in addition to special controls for IPX SAP.
Perform the following steps to configure EIGRP for IP:
1. Use the following to enable EIGRP and define the autonomous system.
Router(config)#router eigrp autonomous-system-number
The autonomous-system-number is the number that identifies the autonomous system. It
is used to indicate all routers that belong within the internetwork. This value must match all routers within the internetwork.
2. Indicate which networks belong to the EIGRP autonomous system on the local router.
Router(config-router)#network network-number
The network-number determines which interfaces of the router are participating in
EIGRP and which networks are advertised by the router.

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