I wish ICANN would finally give us some real "reserved" internal TLDs, but we do have a few we can work with:
RFC 2606 https://tools.ietf.org/html/rf...
test, example, invalid, localhost
"gTLD Applicant Guidebook", Section 188.8.131.52.1 "Reserved Names" http://newgtlds.icann.org/en/a...
afrinic, iana-servers, nro, alac, icann,
rfc-editor, apnic, iesg, ripe, arin, ietf,
root-servers, aso, internic, rssac, ccnso,
invalid, ssac, example*, irtf, test*, gac,
istf, tld, gnso, lacnic, whois, gtld-servers,
local, www, iab, localhost, iana, nic
Most of those aren't really suitable for internal network names except perhaps "tld" and "local" but we can't use "local" because of multicast dns... but that RFC does reference some other names we're PROBABLY safe to use:
RFC 6762 http://tools.ietf.org/html/rfc...
intranet, internal, private, corp, home, lan
It'd be great if we could just get the alternate example domains from RFC 6762 explicitly reserved.