Cisco 300-410 - Implementing Cisco Enterprise Advanced Routing and Services (300-410 ENARSI)

When you configure an EIGRP summary route, all networks that fall within the range of your

summary are suppressed and no longer advertised on the interface. Only the summary route is

advertised. But if we want to advertise a network that has been suppressed along with the

summary route then we can use leak-map feature. The below commands will fix the

configuration in this question:

R1(config)#access-list 1 permit 10.1.1.0 0.0.0.3

R1(config)#route-map Leak-Route permit 10 // this command will also remove the “route_map

Leak-Route deny 10” command.

R1(config-route-map)#match ip address 1

By default BGP advertises all prefixes to external BGP neighbors. This means that if you are

multi-homed (connected to two or more ISPs) then you might become a transit AS. For example,

ISP 2 in AS 200 can send traffic to your router in AS 100 to reach ISP 3 in AS 300 because you

advertised prefixes in ISP 3 to ISP 2.

This is what will be seen in the BGP routing table of ISP1:

When you configure an EIGRP summary route, all networks that fall within the range of your

summary are suppressed and no longer advertised on the interface. Only the summary route is

advertised. But if we want to advertise a network that has been suppressed along with the

summary route then we can use leak-map feature. The below commands will fix the

configuration in this question:

R1(config)#access-list 1 permit 10.1.1.0 0.0.0.3

R1(config)#route-map Leak-Route permit 10 // this command will also remove the “route_map

Leak-Route deny 10” command.

R1(config-route-map)#match ip address 1

The reason for the loop is that R2 is forwarding the packets destined to 10.1.1.1 to R4, instead of R1. This is because in the redistribute OSPF statement, BW metric has a higher value and delay has a value of 1. So, R2 chooses R4 over R1 for 10.1.1.0/24 subnet causing a loop. Now, R5 learns 10.1.1.0/24 from R3 and advertises the same route to R4, that R4 redistributes back in EIGRP. If R3 sets a tag of 1 while redistributing EIGRP in OSPF, and R4 denies all the OSPF routes with tag 1 while redistributing, it will not advertise 10.1.1.0/24 back into EIGRP. Hence, the loop will be broken.

DHCPACK

The server-to-client communication with configuration parameters, including committed network address.

DHCPINFORM

The client-to-server communication, asking for only local configuration parameters that the client already has externally configured as an address.

DHCPNAK

The server-to-client communication, refusing the request for configuration parameter.

DHCPDECLINE

The client-to-server communication, indicating that the network address is already in use

From the exhibit, we learned:

+ VRF customer_a was exported with Route target (RT) of 1:1 so at the remote site it must be

imported with the same RT 1:1.

+ VRF customer_a was imported with Route target (RT) of 1:1 so at the remote site it must be

exported with the same RT 1:1.

Therefore at the remote site we must configure the command “route-target both 1:1” (which is

equivalent to two commands “route-target import 1:1” & “route-target export 1:1”.

By default, Catalyst switches add a simple uptime timestamp to logging messages. This is a cumulative counter that shows the hours, minutes, and seconds since the switch has been booted up

Explanation

From the output, we learn that the current best path is from 10.57.255.11 (which includes “…valid,

confed-external, best“) and this path is 2 ASes away (64955 65003). Although there are some paths

with only 1 AS away (path from 172.16.254.234 for example) but they were not chosen the best path

so AS_PATH was not used to determine the best path -> Answers A and answer C are not correct.

All the paths in the output have metric of 0 and this is the lowest (best) value for this attribute. If we

configure higher MED then it is less preferred over other paths -> Answer B is not correct.

Only answer D is left but LOCAL_PREF attribute should be configured with higher value to be preferred

so we hope “lower LOCAL_PREF” here means higher value. But this is the best answer.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6_fhsec/configuration/xe-3s/ip6f-xe-3s-book/ip6-ra-guard.html#GUID-589AF00C-7499-439F-AD23-51005D61CAB7

The IPv6 RA Guard feature does not offer protection in environments where IPv6 traffic is tunneled.