Exam CAS-004 topic 1 question 246 discussion

B is the correct response. To me this looks like BGP Prefix list. BGP Prefix lists are important for their high flexibility, support for incremental updates, and that writing BGP Prefix lists are much more efficient than writing ACL’s that filter BGP updates as BGP tables can have much more content (thousands of entries) in them as compared to IGP’s route tables. They have some similarities to ACL’s that will make them a bit easier to worked with Both require a route to explicitly permitted, or it is denied At the bottom of the prefix list is an Implicit deny Explicit deny statements don’t override the implicit deny Prefix lists work from top to bottom until a match is found, and the process stops, so it is important to keep the lines in correct order for the Prefix list to work properly Prefix list lines are numbered, default increment if a number value is not specified, is to increment by 5 (giving the admin wiggle room to insert lines later as needed) according to Wikipedia

Border Gateway Protocol (BGP)

It's B. 0.0.0.0/0 to a public IP indicates this is the default path for traffic. So general internet traffic would take this route, which is indicated to be BGP. Plus, as also mentioned, the others are primarily for internal network routing.

Need to change my first response to C EIGRP. EIGRP contains a topology table, which makes it different from a true distance vector routing protocol. EIGRP’s topology table is a vital component of DUAL and contains information to identify loop-free backup routes. The topology table contains all the network prefixes advertised within an EIGRP autonomous system. 172.16.0.0/24 is subnetted, 4 subnets D 172.16.0.0 [90/156160] via 192.168.12.2, 00:01:07, FastEthernet0/0 D 172.16.1.0 [90/156160] via 192.168.12.2, 00:01:07, FastEthernet0/0 D 172.16.2.0 [90/156160] via 192.168.12.2, 00:01:07, FastEthernet0/0 D 172.16.3.0 [90/156160] via 192.168.12.2, 00:01:07, FastEthernet0/0