# Canonically Unique Host

#### The Basics

A Canonically-unique host is a [FQDN](https://en.wikipedia.org/wiki/FQDN) that will canonically resolve to a designated address or set of addresses. Not to be confused with a @locally-unique-host.

#### In-depth information

A Canonically-unique host is defined by remote authoritative sources; usually through [DNS](https://en.wikipedia.org/wiki/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]\(<https://en.wikipedia.org/wiki/Hosts_(file>))
* an internal-network resolver (which eventually pulls from external sources)

#### Notes

* Haven primarily uses @canonically-unique-host resolution while @I2P only uses @locally-unique-host resolution.
* @I2P's and @Kovri's self-assigned top-level domain is currently `.i2p` and @Kovri intends to only process/use the `.i2p` [top-level domain](https://en.wikipedia.org/wiki/Top_level_domain)