Are underscores no longer supported in Bind 9.4?

Mark Andrews Mark_Andrews at isc.org
Thu Mar 1 05:37:54 UTC 2007


> Bill Larson wrote, on 01. mar 2007 04:54:
> 
> [...]
> 
> >> Haven't begun with 9.4 yet, but shall do shortly. Are underscores
> >> permitted in TXT records? I'm thinking of things like Kerberos and
> >> Domainkeys/DKIM TXT records.
> > 
> > Come on, there is a difference between "hostnames" with an "A" record 
> > and "TXT" records.  This is an argument from the early BIND-8 days.  At 
> > least seven years old.
> > 
> > Please, if you are managing a DNS operation, maybe for Kerberos, you 
> > need to understand the DNS that you are managing.  Do a little 
> > studying.  (You have the exact same issue with "SRV" records used by 
> > Microsoft Active Directory also.  The AD records/domains specifically 
> > include underscore characters.)
> 
> Possibly. Keep things on the list, if you please.
> 
> --Tonni
> 
> -- 
> Tony Earnshaw
> Email: tonni at hetnet dot nl

	Kerberos uses _kerberos specifically because _kerberos is
	not a legal label in a hostname.  You can then have a host
	called kerberos without it clashing the TXT record specifying
	the Kerberos realm.

	e.g.
		kerberos.example.com A 1.2.3.4
		_kerberos.example.com TXT EXAMPLE.COM

	Similarly for SRV, using underscore moves the records out of
	the hostname space.
	
	Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org



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