My final suggestion on the mailing list for solving this was as follows:
"What about if the final part starts with a digit actually checking if the complete name is an IP address e.g. calling InetAddreses.isInetAddress? The discussion section in RFC 1123 does suggest a full syntactic check to prevent a dotted decimal number getting through."
InternetDomainName.isValid returns false for the parameter "8server".
RFC1123 suggests that names should be able to start with a digit. See https://groups.google.com/forum/#!topic/guava-discuss/8Sycya7Fkok on guava-discuss for a discussion of the issue.
I also asked for clarification on Server Fault at http://serverfault.com/questions/638260/is-it-valid-for-a-hostname-to-start-with-a-digit
My final suggestion on the mailing list for solving this was as follows:
"What about if the final part starts with a digit actually checking if the complete name is an IP address e.g. calling InetAddreses.isInetAddress? The discussion section in RFC 1123 does suggest a full syntactic check to prevent a dotted decimal number getting through."
but there was no response.
relevance: 1