Exam 350-501 topic 1 question 91 discussion

i think the correct answer is C: nsf ietf helper strict-lsa-checking as Answer A is an optional Command #nsf ietf helper disable

I agree with Onny. Option C seems to be the correct. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/configuration/15-s/iro-15-s-book/iro-nsf-ospf.html " A change in link-state database contents indicates a network topology change, forcing the termination of the graceful restart process when the strict-lsa-checking option is enabled on the helper. "

The strict link state advertisement (LSA) checking feature allows a helper device to terminate the graceful restart process if the device detects a changed LSA that would cause flooding during the graceful restart

Link provided proves C

The link provided shows that C is the answer.

The answer correct is C, Graceful restart helper mode is enabled by default. It is not recommended to disable helper mode because the disabled neighbor will detect the lost adjacency and the graceful restart process will be terminated. The strict LSA checking feature allows a helper router to terminate the graceful restart process if it detects a changed LSA that would cause flooding during the graceful restart process.

wow this was explain so well on the comments here theres no reason to look at the links!

I also agree with Onny. If we refer to the link below and Fulano_de_tal, it is obviously C: https://www.cisco.com/c/en/us/td/docs/ios/12_4t/ip_route/configuration/guide/tgrhelp.html#wp1067091 To configure strict LSA checking on both NSF-aware and NSF-capable routers, enter the nsf ietf helper strict-lsa-checking command on the router. However, strict LSA checking will not become effective until the router becomes a helper router during an IETF graceful restart process. With strict LSA checking enabled, the helper router will terminate the helpering process of the restarting router if it detects that there is a change to an LSA that would be flooded to the restarting router, or if there is a changed LSA on the retransmission list of the restarting router when the graceful restart process is initiated.

#nsf ietf helper disable this Command is issued by default, The Command Default : IETF NSF helper mode is disabled. in this Question didn't mention that anyone enabled it, so why choose A and disable it again