Cisco Updated 350-501 Exam Questions and Answers by sahib

 The ttl-security hops  command sets the maximum number of hops that a BGP message can traverse. In this case, setting ttl-security hops 2 means that the router will accept BGP packets from a neighbor (2.2.2.2) only if the TTL is 253 or more. This is because the default TTL value is 255, and for each hop, the TTL is decremented by 1. Therefore, a packet from a directly connected neighbor would have a TTL of 254 when it reaches the PE router. If the packet has traversed one more router (making it two hops away), the TTL would be 253 upon arrival.

References: This information is based on the TTL security mechanism described in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) training materials,

The issue is that router R2 is not installing the network 172.16.33.1/32 in the routing table due to an incorrect access list configuration. The correct answer is option C, which will allow the network to be installed in the routing table by permitting addresses from 172.16.33.0 to 172.16.33.255 with a wildcard mask of 0.0.0.255.

The current access list on R2, “access-list 1 permit 172,16,32,0 0,0,0,255”, only permits addresses from the range of 172,16,32,0 to 172,16,32,255 due to its wildcard mask of “0,.0,.0,.255”. This does not include the address “172,.16,.33,.1”.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) study guide or course materials available on Cisco’s official website or authorized training partners.

LDP session protection capability is a feature that maintains LDP bindings when a link fails, using LDP Targeted Hellos to protect LDP sessions. Without the specific exhibit, it’s not possible to determine which router has LDP session protection enabled but session hold up is not active.

References: Information about MPLS LDP Session Protection can be found in Cisco documentation, such as the Cisco IOS MPLS Configuration Guide.