1.4 Relationship to Protocols and Other Structures
Various protocols use host names in their own protocols and it is the responsibility of those protocols to state whether they use the standard host name syntax, or this extended syntax.
One protocol worth noting is the DNS protocol [RFC1034] [RFC1035] [RFC2181], which does not depend on host names in any way. The DNS protocol uses DNS names, which allow binary labels, and hence inherently supports host names as well as names that would not be legal host names.
Note This document does not apply to NetBIOS names, which are instead discussed in [MS-NBTE].