its not hierarchically wrong; services never required their own subdomain - example.com is just as valid a host as www.example.com
sure it is helpful for organization, but when was the last time you used ssh.example.com?
sure it is helpful for organization, but when was the last time you used ssh.example.com?
RFC 1034[0] however, argues for a tree-based structure and lays emphasis on the value of branching. It being 'wrong' might have been too strong a description, how about it being 'improper'?
When I've seen SSH access being offered as a network service and not as a means to administrate other services on a network it's often been under names such as 'shell.example.com' - not exactly your 'ssh' label but an approximation.