Complex sentence: The hosts/networks nameserver functionality NIS or LDAP can provide is probably better handled by DNSSEC servers when used on large LANs, leaving just site-wide identification information for NIS masters and slave machines to serve.
Split into simpler sentences: The hosts/networks nameserver functionality NIS or LDAP can provide, is probably better handled by DNSSEC servers when used on large LANs. Leaving just site-wide identification information for NIS masters and slave machines to serve.