-----BEGIN PGP SIGNED MESSAGE----- Hash: RIPEMD160 Bill Moran wrote: > In response to Christopher Key <[EMAIL PROTECTED]>: > >> Hello, >> >> I've a host on the network called "GC100_000C1E00AC3F_GlobalCache", and >> I'm getting interesting behaviour when I try to do DNS lookups on it. >> >> Under FreeBSD, ping fails with 'Unknown server error'(distinct from the >> standard 'Unknown host'), and nslookup succeeds. OSX and Windows >> machines will do a DNS lookup on it quite happily >> >> The best explanation I can manage is that ping etc. are using different >> code from nslookup, and only nslookup is allowing the underscores within >> the hostname. >> >> Is this behaviour by design? My understanding is that underscores are >> not strictly permitted, but that most implementations choose to allow >> them unless there's a specific reason not to. > > I had this discussion with some colleagues a short time back. Our > conclusion (based on some research and experimentation): > 1) Underscores are not valid in domain names. > 2) _most_ DNS systems will work with them anyway. > 3) Just enough DNS systems don't work with _, that it's a really bad > idea to use them in domain names. >
DNS is perfectly happy with underscores in RRs generally -- it's just forbidden for them to appear in hostnames in the DNS specifically. This is to distinguish between hostnames and other data such as SRV records. Cheers, Matthew - -- Dr Matthew J Seaman MA, D.Phil. Flat 3 7 Priory Courtyard PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate Kent, CT11 9PW, UK -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEAREDAAYFAkghqO4ACgkQ3jDkPpsZ+VZBewCdHQWo8t2uUoAktf84NdTG6CKX FIwAoIBMMlu9k6+8N1Wypz0Wm33v7VuD =fU7u -----END PGP SIGNATURE----- _______________________________________________ email@example.com mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"