Windows Domain Name Length Limit. But that is not correct. The restrictions in the preceding table are for the host name.
PathFilename limit is 260 characters. Its the number of octets. When you create a virtual machine in the portal the same value is used for both names.
The Windows 10 Anniversary Update finally adds the option to abandon that.
The maximum length of the host name and of the fully qualified domain name FQDN is 63 bytes per label and 255 characters per FQDN. Only letters numbers or dashes can be used. There is a limit of approximately 1 billion security identifiers SIDs over the life of a domain. Maximum Path Length Limitation In the Windows API with some exceptions discussed in the following paragraphs the maximum length for a path is MAX_PATH which is defined as 260 characters.