That's only required when the Alfresco server is running on Windows, to avoid collisions with Windows' built in CIFS server. When Alfresco is installed on a non-Windows OS however all that's required is that the hostname that the clients use resolves to an IP address via DNS / hosts / wotnot (in fact in this case using serverA probably won't work - chances are that that hostname isn't configured in DNS and so won't resolve).
Cheers,
Peter