Some NFS servers support an auxiliary NFSv3 ACL protocol that
Sun added to Solaris but never became an official part of the
NFS version 3 protocol. This protocol extension allows
applications on NFS clients to manipulate POSIX Access Control
Lists on files residing on NFS servers. NFS servers enforce
ACLs on local files whether this protocol is available or not.

Choose Y here if your NFS server supports the Solaris NFSv3 ACL
protocol extension and you want your NFS client to allow
applications to access and modify ACLs on files on the server.

Most NFS servers don't support the Solaris NFSv3 ACL protocol
extension. You can choose N here or specify the "noacl" mount
option to prevent your NFS client from trying to use the NFSv3
ACL protocol.

If unsure, say N.