Path: vixie!Pa.dec.com!bind-redist-request
From: bryan@notorious.rs.itd.umich.edu (Bryan Beecher)
Newsgroups: local.mail.dns.bind
Subject: When and why to use glue (was glue)
Date: 2 Mar 1994 07:37:27 -0800
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hamjavar@unm.edu (Farid Hamjavar) asks:
>
>What's the rule [ for glue ] ?

A glue record is an A record for a name that appears on the right-hand side
of a NS record.  So, if I have this:

	itd.umich.edu.		IN	NS	dns2.itd.umich.edu.
	dns2.itd.umich.edu.	IN	A	141.211.164.3

then the second record is a glue record (for the NS record above it).

You need glue records when -- and only when -- you are delegating authority
to a nameserver that "lives" in the domain you are delegating.  In other
words, in the example above, I need to add an A record for dns2.itd.umich.edu
since it "lives" in the domain it serves.  This boot-strapping information
is necessary:  How am I supposed to find out the IP address of the nameserver
for domain FOO if the nameserver for FOO "lives" in FOO?

If I have this NS record:

	itd.umich.edu.		IN	NS	dns.cs.wisc.edu.

I do NOT need a glue record, and, in fact, adding one is a very bad idea.
If I add one, and then the folks at U Wisconsin change the address, then I am
passing out incorrect data.

Also, unless you actually have a machine called something.IN-ADDR.ARPA, you
will never have any glue records present in any of your "reverse" files.
-- 
Bryan Beecher, U-M Information Technology Division (+1 313 747 4050)
Domain:	Bryan.Beecher@umich.edu      Path:  ..!uunet!destroyer!bryan
