Which of the following statements is true regarding the domain authentication mode md5 hello command in the IS-IS process?

This command enables IS-IS Hello PDUs to carry authentication information. 

IS-IS SNP and LSP can be flooded normally only when the domain authentication mode and password of all routers in the same routing domain are MD5 and hello. 

IS-IS authentication cannot be applied to IPv6 environments. 

Routing domain authentication enables Level-1 and Level-2 SNPs and LSPs to carry authentication information.