[dns-operations] domain in .no, nameserver in .com - where is the glue?

[Mark Andrews]

> Q1:
> How "bad" is it to have a domain's name servers under another TLD?
> For example, apple.no has all NS's under .com.

	If its only one level of indirection its not too bad.  What's
	bad is when the server also need another level of indirection.

	My rule of thumb is "a server should server the zone it lives in".

	This allows for zero or one level of indirection.

	There have been cases that exceeded BIND 8's old limit of
	5 levels of indirection.

	All the servers for apple.no meet this rule of thumb as do the
	servers for apple.com, euro.apple.com and asia.apple.com.

apple.no.		604761	IN	NS	nserver.apple.com.
apple.no.		604761	IN	NS	nserver2.apple.com.
apple.no.		604761	IN	NS	nserver.euro.apple.com.

apple.com.		431946	IN	NS	nserver.euro.apple.com.
apple.com.		431946	IN	NS	nserver2.apple.com.
apple.com.		431946	IN	NS	nserver.apple.com.
apple.com.		431946	IN	NS	nserver.asia.apple.com.
apple.com.		431946	IN	NS	nserver4.apple.com.
apple.com.		431946	IN	NS	nserver3.apple.com.

euro.apple.com.         604800  IN      NS      nserver.euro.apple.com.
euro.apple.com.         604800  IN      NS      nserver2.apple.com.
euro.apple.com.         604800  IN      NS      nserver.asia.apple.com.
euro.apple.com.         604800  IN      NS      nserver3.apple.com.
euro.apple.com.         604800  IN      NS      nserver4.apple.com.
euro.apple.com.         604800  IN      NS      nserver.apple.com.

asia.apple.com.         432000  IN      NS      nserver4.apple.com.
asia.apple.com.         432000  IN      NS      nserver3.apple.com.
asia.apple.com.         432000  IN      NS      nserver.apple.com.
asia.apple.com.         432000  IN      NS      nserver.asia.apple.com.
asia.apple.com.         432000  IN      NS      nserver2.apple.com.

 
> Q2:
> When doing a dig trace for www.apple.no, I don't see any lookups for 
> .com-addresses. How does the resolver find the A record for the name 
> servers?

	It looks up the addresses using gethostbyname/getaddrinfo.
 
> # dig +trace a www.apple.no
> 
> ; <<>> DiG 9.3.3 <<>> +trace a www.apple.no
> ;; global options:  printcmd
> .                       311456  IN      NS      I.ROOT-SERVERS.NET.
> .                       311456  IN      NS      G.ROOT-SERVERS.NET.
> .                       311456  IN      NS      A.ROOT-SERVERS.NET.
> .                       311456  IN      NS      L.ROOT-SERVERS.NET.
> .                       311456  IN      NS      F.ROOT-SERVERS.NET.
> .                       311456  IN      NS      D.ROOT-SERVERS.NET.
> .                       311456  IN      NS      H.ROOT-SERVERS.NET.
> .                       311456  IN      NS      J.ROOT-SERVERS.NET.
> .                       311456  IN      NS      B.ROOT-SERVERS.NET.
> .                       311456  IN      NS      K.ROOT-SERVERS.NET.
> .                       311456  IN      NS      C.ROOT-SERVERS.NET.
> .                       311456  IN      NS      E.ROOT-SERVERS.NET.
> .                       311456  IN      NS      M.ROOT-SERVERS.NET.
> ;; Received 436 bytes from 195.67.199.24#53(195.67.199.24) in 12 ms
> 
> no.                     172800  IN      NS      Y.NIC.no.
> no.                     172800  IN      NS      Z.NIC.no.
> no.                     172800  IN      NS      NOT.NORID.no.
> no.                     172800  IN      NS      NJET.NORID.no.
> no.                     172800  IN      NS      I.NIC.no.
> no.                     172800  IN      NS      X.NIC.no.
> ;; Received 237 bytes from 192.36.148.17#53(I.ROOT-SERVERS.NET) in 19 ms
> 
> apple.no.               86400   IN      NS      nserver.euro.apple.com.
> apple.no.               86400   IN      NS      nserver.apple.com.
> apple.no.               86400   IN      NS      nserver2.apple.com.
> ;; Received 111 bytes from 193.71.199.51#53(Y.NIC.no) in 29 ms
> 
> www.apple.no.           86400   IN      CNAME   euro-red.apple.com.
> euro-red.apple.com.     86400   IN      A       17.254.3.122
> apple.com.              432000  IN      NS      nserver.euro.apple.com.
> apple.com.              432000  IN      NS      nserver.apple.com.
> apple.com.              432000  IN      NS      nserver2.apple.com.
> apple.com.              432000  IN      NS      nserver3.apple.com.
> apple.com.              432000  IN      NS      nserver4.apple.com.
> apple.com.              432000  IN      NS      nserver.asia.apple.com.
> ;; Received 319 bytes from 17.72.133.64#53(nserver.euro.apple.com) in 62 ms
> 
> 
> (The first server queried 195.67.199.24 is my ISP's DNS)

	dig needs to find the list of root servers somehow.
 
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org