A Canonically-unique host is a FQDN that will canonically resolve to a designated address or set of addresses. Not to be confused with a Locally unique host.
A Canonically-unique host is defined by remote authoritative sources; usually through DNS. When resolving a peer's hostname, you will most likely use an external source for resolution unless you have the following implemented:
- a database file similar to a hosts file
- an internal-network resolver (which eventually pulls from external sources)