Cisco (300-410-ENARSI) Exam Questions And Answers page 16

The following commands should be included in the implementation plan:
neighbor 135.90.66.6 route-map set_weight in
match ip-address 1
set weight 100

The neighbor 135.90.66.6 route-map set_weight in command specifies a route-map named set_weight for the incoming routing updates from 135.90.66.6 peer. The match ip-address 1 command specifies a criterion to match the IP address as specified in an access list. When the match criterion is met, the action specified in the set weight command is performed.
The set weight 100 command sets the weight attribute, which is a Cisco-defined attribute, to 100. The weight attribute is the first to be checked when BGP selects the best path between eBGP routers. This attribute is local to the router on which it is set and cannot be advertised to other routers.
The complete set of commands to achieve the desired results is as follows:
access-list 1 permit 10.77.22.0 0.0.0.255
router bgp 444
neighbor 135.90.66.3 remote-as 111
neighbor 135.90.66.1 remote-as 222
neighbor 135.90.66.6 remote-as 333
neighbor 135.90.66.6 route-map set_weight in
route-map set_weight permit 10
match ip-address 1
set weight 100

The set metric 100 command should not be included in the implementation plan to achieve the desired results. This command sets the metric to 100; however, the requirement is to use the first attribute to be checked, which is the weight attribute.
The neighbor 135.90.66.1 route-map set_weight out command should not be included in the implementation plan. This command forms an eBGP neighbor relationship with rtr3. The command also uses a route map named set_weight to set the weight attribute for the routes sent by rtr1. However, the weight attribute is local to rtr1 and cannot be set for outbound routes.
The route-map set_weight deny 10 command should not be specified in the implementation plan to achieve the desired results. This command creates a route map named set_weight. The deny keyword in this command indicates that if the match criterion is satisfied, then the set action is not performed. The permit keyword should be specified instead of the deny keyword to perform the set action when a match occurs.
Objective:
Layer 3 Technologies
Sub-Objective:
Identify suboptimal routing
Cisco > Support > Technology Support > IP > IP Routing > Design > Design Technotes > BGP Case Studies > BGP Case Studies 1 > Route Maps
Cisco > Support > Technology Support > IP > IP Routing > Design > Design Technotes > BGP Best Path Selection Algorithm
Cisco > Support > Technology Support > IP > IP Routing > Design > Design Technotes > BGP Case Studies > BGP Case Studies 2 > Weight Attribute

The autonomous system number (ASN) of rtrA and the best paths between rtrA and the 172.161.81.7 neighbor cannot be determined from the given output.
The show ip bgp neighbors command displays the TCP and BGP connections from a given router to its neighbors. This command is executed in EXEC mode. You can use various optional keywords to view different aspects of the neighbors. For example, this command can display the details about a given neighbor, routes advertised to or received from neighbors, and the prefix-list received by neighbors.
In this case, the command is used to show the details about a specific neighbor of rtrA. The IP address (172.161.81.7) of the neighbor is provided in the command. The text BGP neighbor is 172.161.81.7 indicates the IP address of the neighbor. The text remote AS 151 indicates that the neighbor is in the ASN 151. It can also be determined from the text external link that the neighbor is an eBGP neighbor. For iBGP neighbors, the text internal link will appear. The router ID (RID) of the neighbor can be determined from the text remote router ID 10.8.22.4.
The output also provides details about the state of the BGP connection, which is Established in this case. Furthermore, the duration for which the connection has been established, the duration for which BGP maintains neighbor relationship in the absence of messages, and the keepalive duration are also displayed.
The state of the connection between the local router (rtrA) and the given neighbor (172.161.81.7) can be any of the following:
• Idle Indicates that the local router does not accept any connection from its neighbor
• Idle (admin) Indicates that the connection between the two routers has been shut down administratively by using the neighbor shutdown command
• Connect Indicates that the local router has already sent an connection request to its neighbor
• Active Indicates that the local router is listening for connection requests from the neighbor
• OpenSent Indicates that the local router has sent an OPEN message to its neighbor
• OpenConfirm Indicates that the local router has received a KEEPALIVE or UPDATE message from its neighbor
• Established Indicates that a BGP connection has been successfully created between the local router and its neighbor
The status of the connection between two BGP neighbors can also be viewed by using the show ip bgp summary command, as shown below:

In the above output, it can be determined that the command router bgp 210 was executed on rtrA because the local AS is 210 in the output. It can be determined that the command neighbor 45.1.1.5 shutdown was issued on rtrA because the state of the neighbor relationship with the router at 45.1.1.5 is listed as IDLE(ADMIN).
All the other options are incorrect because the respective details are displayed by the show ip bgp neighbors command.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify eBGP (IPv4 and IPv6 address families)
Cisco IOS IP Routing: BGP Command Reference > show ip bgp neighbors
Cisco > Cisco IOS IP Routing: BGP Command Reference > show ip bgp summary

The correct answer is that IPv4 and IPv6 are running simultaneously on rtrA. The set of commands enables IPv6 on the rtrA router and assigns an IPv4 address and an IPv6 address to the Fa0/0 interface. This indicates that the router is a dual-stack router on which both IPv4 and IPv6 are running simultaneously.
The IPv4 address is not translated to the IPv6 address by the given set of commands because NAT-PT is not enabled on the router. To enable NAT-PT on a router, you need to use the ipv6 nat command. In addition, the ipv6 nat prefix command should be used to specify an IPv6 prefix.
The IPv6 address is not an IPv4-compatible address. IPv4-compatible IPv6 addresses are used in automatic IPv4-compatible IPv6 tunnels. These addresses refer to those IPv6 unicast addresses that have zeros in the first 96 bits and an IPv4 address in the last 32 bits. For example, 0:0:0:0:0:0:192.156.10.67 is an IPv4-compatible IPv6 address where 192.156.10.67 is an IPv4 address. The IPv6 address (2001:0:1:1:D52::F3C/64), in this case, is not an IPv4-compatible IPv6 address.
A tunnel is not created for the interoperability of the IPv4 and IPv6 addresses because the given set of commands configures the router as a dual-stack router. There are no commands for configuring a tunnel on the router.
Objective:
Network Principles
Sub-Objective:
Recognize proposed changes to the network
Cisco IOS IPv6 Configuration Guide, Release 12.4 > Implementing IPv6 Addressing and Basic Connectivity > Configuration Examples for Implementing IPv6 Addressing and Basic Connectivity > Example: Dual Protocol Stacks Configuration

The missing autonomous system number (ASN) in the AS_PATH parameter of Path3 should be 40 so that Path3 becomes the best path from A to B. BGP selects the best path by first selecting the first valid path between two routers. If other paths are available between the two routers, BGP compares values of various attributes to select the best available path. In this case, Path 2 is the current best path between routers A and B. The values of various parameters (listed in the table) are compared with Path1 and Path2.
While comparing Path1 and Path2, the weight, LOCAL_PREF, local originate source command, length of AS_PATH, and origin type are same. Therefore, these parameters are not useful in determining the best path. However, the MED value of Path2 is lower than that of Path1. As a result, Path2 is selected as the best path because BGP prefers the route with the lesser MED value.
BGP now compares the parameter values of Path 2 (the current best path) and Path3. The weight and LOCAL_PREF parameters are same for both routes. Path 2 and Path3 are both local routes originated by using the redistribute and the network commands, respectively. BGP prefers local routes learned by the network or redistribute commands over those that are learned by the aggregate-address command.
The AS_PATH parameter specifies the list of AS numbers that comprise the route. The best path should have the shortest value for the AS_PATH parameter. In this case, both Path2 and Path3 consist of three AS numbers and are originated by an IGP. Therefore, the AS_PATH and the origin type parameters are not helpful in determining the best path.
Finally, BGP compares the MED values of Path2 and Path3. The MED values are compared only when the first AS number in the AS_PATH is the same for both routes; that is, when both routes begin in the same AS. The first ASN in the AS_PATH parameter of Path2 is 40; therefore, the missing ASN for Path3 should be 40. This allows the comparison of MED values and the selection of Path3 as the best route as it has lower MED value.
All the other options are incorrect because a value other than 40 disables the comparison of the MED values between Path2 and Path3. If the MED value is not considered, then BGP determines whether Path3 is an iBGP or eBGP router. BGP selects an iBGP route instead of an eBGP route.
Objective:
Layer 3 Technologies
Sub-Objective:
Explain BGP attributes and best-path selection
Internetworking Technology Handbook > BGP > BGP attributes

By default, Type 5 link-state advertisements (LSAs) do not include directly connected networks. To alter this behavior, you must execute the redistribute connected command in OSPF configuration mode. This command instructs the router to include these local interfaces in its advertisements, as follows:
RTA10(config)# router ospf 1
RTA10(config-router)# redistribute connected

You should not execute the command set that includes the redistribute static command. This instructs the router to advertise any statically defined routes that have been configured, instead of those that are local to the router.
You should not execute the command set that includes RTA10(config)# redistribute connected. The redistribute connected command is shown being executed at the wrong command prompt, and will generate an error message. It must be executed in the OSPF configuration mode and not global configuration mode.
You should not execute the following command set:
RTA10(config)# router ospf 1
RTA10(config-router)# network 192.168.5.0 0.0.0.0 area 1
RTA10(config-router)# network 192.168.6.0 0.0.0.0 area 1

The network commands will cause the networks to receive updates from the router, but do not allow them to be advertised in Type 5 LSAs.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify redistribution between any routing protocols or routing sources
Cisco > Home > Support > Technology Support > IP > IP Routing > Design > Design Technotes > Redistributing Connected Networks into OSPF

Despite the inclusion of the command aggregate-address 192.168.5.0 255.255.252.0, all subnets of the aggregate route will also be placed in the routing updates because of the omission of the summary-only keyword. Therefore, 192.168.5.4/29, 172.16.5.0/16, 192.168.6.0/24 and 192.168.7.0/24 will be present.
Had the following command been executed, the subnet addresses would not appear in the routing table of the router at 172.16.5.2:
Router5(config-router)# aggregate-address 192.168.5.0 255.255.252.0 summary-only
Therefore, both the aggregate address and all of the 192.168.0.0 subnets will be in the routing table.
The 172.16.5.0/24 network will be in the routing table of the router at 172.160.5.1 because it is directly connected.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify manual and autosummarization with any routing protocol
Cisco > Cisco IOS IP Routing: BGP Command Reference > aggregate-address

The area virtual-link command should specify the area to be traversed and the ID of the router to which the router being configured will connect. Therefore, the correct answer is:
RouterA(config-router)# area 2 virtual-link 165.165.10.12
RouterB(config-router)# area 2 virtual-link 165.165.20.15

A virtual link is used to make a virtual connection of an area border router (ABR) to the backbone. It is used in situations where an area does not physically border the backbone area. The virtual link provides logical connectivity of the area to the backbone. If the virtual link appears not to be functional, which would manifest itself in Router A not having all of Router B's networks in its routing table, the state of the link can be verified on Router A by executing the show ip ospf virtual-link command. An example is shown below. The state of the link as shown in line 1 of the output should be up.
RouterA# show ip ospf virtual-links
Virtual Link to router 172.16.8.2 is up
Transit area 0.0.0.1, via interface Ethernet0, Cost of using 10
Transmit Delay is 1 sec, State POINT_TO_POINT
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 0:00:08
Adjacency State FULL

The configuration below is incorrect because area 0 is referenced in the second line. It should reference area 2, the area being traversed.

RouterA(config-router)# area 2 virtual-link 165.165.10.12
RouterB(config-router)# area 0 virtual-link 165.165.20.15

The configuration below is incorrect because area 0 is referenced in the first line. It should reference area 2, the area being traversed.
RouterA(config-router)# area 0 virtual-link 165.165.20.15
RouterB(config-router)# area 2 virtual-link 165.165.10.12

The configuration below is incorrect because area 0 is referenced in both lines. Both should reference area 2, the area being traversed.
RouterA(config-router)# area 0 virtual-link 165.165.10.12
RouterB(config-router)# area 0 virtual-link 165.165.20.15

If the virtual link is incorrectly configured the following error will be generated:
*Dec 10 00:31.146: %OSPF-4-ERRRCV: Received invalid packet mismatch area ID, from backbone area must be virtual link but not found from 165.165.10.5, Serial 0

Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify network types, area types, and router types
Cisco > Home > Support > Technology Support > IP Routing > Design > Design Technotes > What Are OSPF Areas and Virtual Links?

R2 can establish a full adjacency with the neighbor at 192.168.5.107 and the neighbor at 192.168.5.165. In a broadcast, multi-access network OSPF network, full adjacencies can only be established with a designated router (DR) or a backup designated router (BDR).
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify OSPF neighbor relationship and authentication
Home.Support > Technology Support > IP > IP Routing > Design > Design Technotes > What does the show ip ospf neighbors command reveal?
Cisco > Cisco IOS IP Routing: OSPF Command Reference > show ip ospf neighbor

The partial output of the show run command indicates that the port number of the HTTPS interface has been changed to 1025. This is indicted by the presence of this command in the configuration:
ip http secure-port 1025

That is not the default port configuration of 443. Therefore, anyone wishing to connect to the secure server will need to reference the new port number in the command. If you change the HTTPS port number, clients attempting to connect to the HTTPS server must specify the port number in the URL, in this format:
https://device:port_number

In this syntax, port_number is the HTTPS port number.
It will not help for the technician to reference port 443 in the command, because that is no longer the port number of the secure server. It is now 1025.
It is not required to disable the HTTP server to use the HTTPS server, although it is a best practice to do so.
There is no need to enable the secure server. We can see it has been enabled by the presence of this command in the configuration:
ip http secure-server

Objective:
Infrastructure Services
Sub-Objective:
Configure and verify device management
Cisco IOS HTTP Services Command Reference > clear ip http client cookie through show ip http server secure status > ip http secure-port

The auto-summary command can affect which networks, identified by using the network command, will be advertised. Using the existing BGP configuration, the router will not announce the 172.16.16.0/24 subnet. Instead, it will announce the classful address 172.16.0.0/16 when the IP routing table maintained by the IGP contains any subnet of that classful address.
The network command directly affects what network is advertised in BGP. If the network command does not also include a network mask, and if auto-summary is enabled, the classful address of 172.16.0.0/16 is advertised any time that the router learns about a 172.16.0.0 subnet via its Interior Gateway Protocol (IGP), such as OSPF or EIGRP. In the exhibit, the routing table does contain entries of the 172.16.16.0/24 and 172.16.24.0/24 subnets that were learned by using the IGP.
If auto-summary is disabled by using the no auto-summary command, only networks in the routing table that are exact matches to the network commands are advertised. For example, to have the router announce only the 172.16.16.0/24 subnet learned via its IGP, you should alter the network command's IP address and include the subnet mask as follows:
network 172.16.16.0 mask 255.255.255.0

A combination of network statements and route statements can be used to advertise a subset of networks that exist. Examine the output shown below:
router bgp 68410
network 192.168.24.0 255.255.252.0
neighbor 172.16.8.5 remote-as 68441
ip route 192.168.24.0 255.255.252.0 null 0

The router is configured to advertise a summary route to the network 192.168.24.0 255.255.252.0. Consider the following networks:
192.168.24.0/24
192.168.25.0/24
192.168.26.0/24
192.168.32.0/24
If this router was connected to those networks, and received a packet destined for 192.168.25.1, it would successfully route the packet because the summary address (where the summarization is the result of the mask 255.255.252.0) is designed to include all of the subnets above except for 192.168.32.0/24. Therefore, all subnets except 192.168.32.0/24 will be advertised by the network and ip route statements with the summary mask.
Note: Whenever changes are made to a routing policy or to an access list that is used by a routing policy, the change will not be reflected in the routing tables of the receiving routers until the BGP session has been cleared with the clear ip bgp command.
The BGP synchronization rule specifies that networks will not be advertised or used via iBGP unless it also has been learned through an IGP. If synchronization is disabled, iBGP will advertise a network without also learning it through an IGP.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify eBGP (IPv4 and IPv6 address families)
Cisco IOS Master Command List > a through b > BGP Commands: A through B > auto-summary (BGP)
Cisco > Cisco IOS IP Routing: BGP Command Reference > router bgp
Cisco > Cisco IOS IP Routing: BGP Command Reference > network (BGP and multiprotocol BGP)