A fully qualified domain name is "myhost.example.com.". It therefore uniquely defines the device — whilst there might be many hosts in the world called "myhost", there can only be one "myhost.example.com.".
Notice that there is a dot at the very end of the domain name, i.e. it ends ".com." and not ".com" — this indicates that the name is an FQDN. For example "myhost.bar.com" could be ambiguous, because it could be the prefix of a longer domain name such as "myhost.bar.com.au", whereas "myhost.bar.com." is a fully qualified domain name (or FQDN) is an unambiguous domain name that specifies the node's position in the DNS tree hierarchy absolutely. To distinguish an FQDN from a regular domain name by its absoluteness; a suffix will not be added.
For example, given a device with a hostname of "myhost" and a domain name of "example.com", the fully qualified domain name is "myhost.example.com.". It therefore uniquely defines the device — whilst there might be many hosts in the world called "myhost", there can only be one "myhost.example.com.".
Notice that there is a dot at the very end of the domain name, i.e. it ends ".com." and not ".com" — this indicates that the name is an FQDN. For example "myhost.bar.com" could be ambiguous, because it could be the prefix of a longer domain name such as "myhost.bar.com.au", whereas "myhost.bar.com." is a fully qualified domain name. Technically, the dot comes before the empty label indicating the root of the Domain Name System hierarchy, and so an FQDN is 255 bytes, with an additional restriction to 63 bytes for each label within the domain name. The syntax of domain names to include non-ASCII characters, by encoding Unicode characters into byte strings within the normal FQDN character set. As a result, the character length limits of internationalized
