Oldie: underscores in 'names ... on -stable?
cswiger at mac.com
Mon Sep 12 18:21:08 PDT 2005
Torfinn Ingolfsen wrote:
[ ... ]
> If I try it with ping in a shell (on FreeBSD), it also fails.
> However both 'host' and 'nslookup' happily foes a lookup of that name.
> so it seems that our resolver (on FreeBSD) is to blame.
> I have seen a few old (ok, from 2003) mailing list posts, which seems to
> indicate that the official rules says that 'underscores are not allowed
> in hostnames'. Is this still the case?
Yes, underscores are not valid characters for hostnames, per RFC 822 and
others. The underscore was not permitted because it is easily confusable with
a hyphen or minus sign, BTW.
> If so, why is FreeBSD in rwo minds about it (nslookup and host working,
> resolver not)?
nslookup, dig, and so forth perform DNS queries directly, bypassing the system
resolver (and flat files like /etc/hosts), and do not perform sanity checking
of the results because these tools are intended for debugging DNS problems.
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