Which description about ISIS extension feature is true? (Multiple choice)

Which description about ISIS extension feature is true? (Multiple choice)
A . ISIS can choose whether verification to received SNP and LSP data packets.
B . When the amount of information which ISIS will publish in link-state protocol data packet PDU is too large, ISIS router will generate multiple LSP fragment, to carry more ISIS information.
C . After enabled router LSP fragment extension function, don’t need to restart ISIS process, you can use this feature.
D . If there are other vendors equipment on the network and does not support the LSP fragment function, must configure the fragment extension mode to Mode-1, or the other vendor’s device can’t identify the message.

Answer: ABD