Which two statements about IS-IS are correct? (Choose two.)
Which two statements about IS-IS are correct? (Choose two.)
PSNPs are used for acknowledging a received LSP. They can also request a missing LSP by listing the necessary sequence numbers. This makes option B and option C correct. CSNPs, on the other hand, provide summaries of LSPs but do not request or acknowledge missing LSPs.
https://bethepacketsite.wordpress.com/2016/08/04/is-is-csnp-and-psnp-packets/ Correct B,C