underscores in hostname

Kevin Darcy kcd at daimlerchrysler.com
Fri Mar 23 19:17:18 UTC 2001

Pete Peterson wrote:

> When I first ran into this problem after inheriting a zone with bad names,
> I discovered that BIND would wouldn't accept A-records with underscores,
> but WOULD accept CNAMES with underscores.  I made a script which changed
> the underscores to hyphens and then added a CNAME with the underscored
> version.  This gave time to phase out the bogus names while keeping BIND
> happy.  This still works fine with 8.2.3; I haven't any 9.x nameservers
> yet.

It makes perfect sense for underscores to be legal in CNAMEs, since the
underscore prohibition is a *hostname* prohibition, and CNAMEs can point to
*any* name in the DNS, regardless of whether that name happens to be a
"hostname", i.e. regardless of whether it owns an address record or not. If
BIND 9 started disallowing underscores in CNAMEs, I'd consider that a bug...

- Kevin

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