OK, after asking my last question, I've done some digging and I think I've figured out how everything works, but there are some things about glue records I haven't quite figured out.
If a resolver tries to resolve ourdomain.com
, at some point it will query a gTLD server, which will return some NS records. In our case, the result should look like this:
% dig +norecurse ourdomain.com @a.gtld-servers.net
;; AUTHORITY SECTION:
ourdomain.com. 172800 IN NS ns1.the-isp.net.
ourdomain.com. 172800 IN NS our-server.ourdomain.com.
;; ADDITIONAL SECTION:
ns1.the-isp.net. 172800 IN A nnn.nnn.nnn.nnn
our-server.ourdomain.com. 172800 IN A mmm.mmm.mmm.mmm
I gather that there are glue records on each gTLD server that associate the two name servers with the IP addresses.
- Do the glue records have TTL's? (Is that what the
172800
is in theADDITIONAL SECTION
?) - If so, what happens when the glue record expires? Suppose the glue record for
our-server.ourdomain.com
expires. Would the gTLD server then do a lookup on that name to find the IP address (which, in this case, would have to go throughns1.the-isp.net
, I think)? If that query results in a different IP address, does the glue record then get changed? If that isn't how it works, then do glue records have to be changed manually, or is there some other mechanism that would cause it to change?