[Novalug] Domain name registrar recommendation request

Rich Kulawiec rsk@gsp.org
Sat Nov 21 10:07:50 EST 2015


On Sat, Nov 21, 2015 at 09:25:11AM -0500, John Covici via Novalug wrote:
> OK, what the heck is a glue record?

I'm going to gloss/simplify this greatly.

Suppose that example.com has authoritative nameservers ns1.example.com
and ns2.example.com.  In other words, example.com's nameservers reside
in the example.com domain, not somewhere else.

1. Someone tries to look up a DNS record (an A record, an MX record, etc.)
for something in example.com.  The query recurses and eventually it
turns out, of course, that the nameservers to ask are ns1.example.com
and ns2.example.com.

2. In order to send a DNS query to either one of those, we need to know
its IP address.

3. In order to know that IP address of ns1/ns2.example.com, we need to
ask the authoritative nameservers for example.com.  Return to step 1.

Glue records solve this problem by providing the IP addresses of
ns1/ns2.example.com in the root zone, so that instead of step 3
sending us in a loop, the query ("what is the A record for
ns1/ns2.example.com?") returns an answer.

To see this in action, try using https://mebsd.com/glue
and give it the domain I'm sending from and the domain
that this mailing list is hosted on.  The former has no
glue records; the latter has three.

---rsk




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