Exam 350-501 topic 1 question 315 discussion

Step-1: By default, the router fetches ROAs (Route Origin Authorization) from the validator but does not begin using them until it is configured to do so. As a result, these prefixes are marked as ‘D’ or disabled. RP/0/RP0/CPU0:Cisco8000#show bgp origin-as validity Status codes: s suppressed, d damped, h history, * valid, > best i - internal, r RIB-failure, S stale, N Nexthop-discard Origin codes: i - IGP, e - EGP, ? - incomplete Origin-AS validation codes: V valid, I invalid, N not-found, D disabled Network Next Hop Metric LocPrf Weight Path D*> 203.0.113.0/24 10.0.12.2 0 0 8100 ? D*> 203.0.113.1/24 10.0.12.2 0 0 8100 ? D*> 192.168.122.1/32 10.0.12.2 0 0 8100 ?

Step-2: In order to enable the router for as-origin validity check, activate this command for the concerned address family. router bgp 100 address-family ipv4 unicast bgp origin-as validation enable When you activate this command, it causes the router to scan the prefixes present in its BGP table against the ROA information received from the validator and one of the three states is assigned to prefixes . RP/0/RP0/CPU0:Cisco8000#show bgp origin-as validity Origin-AS validation codes: V valid, I invalid, N not-found, D disabled Network Next Hop Metric LocPrf Weight Path V*> 203.0.113.0/24 10.0.12.2 0 0 8100 ? I* 203.0.113.1/24 10.0.12.2 0 0 8100 ? N*> 192.168.122.1/32 10.0.12.2 0 0 8100 ?

Step-3: In order to enable the router to use prefix validation state information while making the best path calculation, this command is needed. This is not enabled by default as it gives you the option of not using the validity information for best path calculation but still allowing you to use it in route policies which are discussed later in this document. router bgp 100 address-family ipv4 unicast bgp bestpath origin-as use validity ! RP/0/RP0/CPU0:Cisco8000#show bgp 203.0.113.0/24 Thu Jan 21 05:30:13.858 UTC BGP routing table entry for 203.0.113.0/24 Versions: Process bRIB/RIB SendTblVer Speaker 31 31 Last Modified: Jan 21 00:03:33.344 for 05:26:40 https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/217020-bgp-rpki-with-xr7-cisco8000-whitepaper.html

This is not included in the Cisco SPCORE e-learning syllabus. Following the explanation, I will go for D

is the first command required to use the requested feature

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/217020-bgp-rpki-with-xr7-cisco8000-whitepaper.html By default, the router fetches ROAs from the validator but does not begin using them until it is configured to do so. As a result, these prefixes are marked as ‘D’ or disabled... In order to enable the router for as-origin validity check, activate this command for the concerned address family. router bgp <#AS> address-family ipv4 unicast bgp origin-as validation enable it causes the router to scan the prefixes present in its BGP table against the ROA information received from the validator and one of the three states is assigned to prefixes. In order to enable the router to use prefix validation state information while making the best path calculation, this command is needed. router bgp <#AS> address-family ipv4 unicast bgp bestpath origin-as use validity I would go for D, since it just need to scan the prefix

According to the Link posted it says: In order to enable the router for as-origin validity check, activate this command for the concerned address family. router bgp 100 address-family ipv4 unicast bgp origin-as validation enable ! Then it says: When you ""activate this command"", it causes the router to scan the prefixes present in its BGP table against the ROA information received from the validator and one of the three states is assigned to prefixes . RP/0/RP0/CPU0:Cisco8000#show bgp origin-as validity !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! In the exhibit you see the following CLI Command: show bgp origin-as validity This would mean the feature is already enabled, otherwise you won't be able to check/execute show bgp origin-as validity So, I would go for D.

got this on the exam, 'D' is correct (you can ignore the typo here, it is correctly spelled on the exam) D - is enabling the feature A - is using it for best-path calculation see: https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/217020-bgp-rpki-with-xr7-cisco8000-whitepaper.html

i go for A. mistmatched in the name of the router in the prompt