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Re: g.root-servers.net returns NXDOMAIN for com.

  • From: jmalcolm
  • Date: Fri Aug 04 10:20:05 2000 
Chris Adams writes:
>Do you see g.root-servers.net listed?  Then why are you asking it about
>com?

Because it is a root server. Note its appearance in the set of NS
records below for ',', for example.

If you ask g about 'com', and instead of giving an answer like the one
a.ROOT-SERVERS.NET gave you, it says it *does not exist*, you will,
correctly, assume that means it doesn't exist and neither do any
subdomains.

Hence, if you randomly query the one server that is returning NXDOMAIN
for com, all com lookups will fail.

Servers must be able to follow the delegation chain, which starts at
the root. The fact that a.ROOT-SERVERS.NET thinks  g.root-servers.net
is not authoritative doesn't matter much if you ask g and it does
think it is authoritative.

[email protected] [~] [main] 2-875> dig ns @a.ROOT-SERVERS.NET . 

; <<>> DiG 8.2 <<>> ns @a.ROOT-SERVERS.NET . 
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
;; flags: qr aa rd; QUERY: 1, ANSWER: 13, AUTHORITY: 0, ADDITIONAL: 13
;; QUERY SECTION:
;;      ., type = NS, class = IN

;; ANSWER SECTION:
.                       6D IN NS        A.ROOT-SERVERS.NET.
.                       6D IN NS        H.ROOT-SERVERS.NET.
.                       6D IN NS        C.ROOT-SERVERS.NET.
.                       6D IN NS        G.ROOT-SERVERS.NET.
.                       6D IN NS        F.ROOT-SERVERS.NET.
.                       6D IN NS        B.ROOT-SERVERS.NET.
.                       6D IN NS        J.ROOT-SERVERS.NET.
.                       6D IN NS        K.ROOT-SERVERS.NET.
.                       6D IN NS        L.ROOT-SERVERS.NET.
.                       6D IN NS        M.ROOT-SERVERS.NET.
.                       6D IN NS        I.ROOT-SERVERS.NET.
.                       6D IN NS        E.ROOT-SERVERS.NET.
.                       6D IN NS        D.ROOT-SERVERS.NET.

;; ADDITIONAL SECTION:
A.ROOT-SERVERS.NET.     6D IN A         198.41.0.4
H.ROOT-SERVERS.NET.     6D IN A         128.63.2.53
C.ROOT-SERVERS.NET.     6D IN A         192.33.4.12
G.ROOT-SERVERS.NET.     6D IN A         192.112.36.4
F.ROOT-SERVERS.NET.     6D IN A         192.5.5.241
B.ROOT-SERVERS.NET.     6D IN A         128.9.0.107
J.ROOT-SERVERS.NET.     5w6d16h IN A    198.41.0.10
K.ROOT-SERVERS.NET.     5w6d16h IN A    193.0.14.129
L.ROOT-SERVERS.NET.     5w6d16h IN A    198.32.64.12
M.ROOT-SERVERS.NET.     5w6d16h IN A    202.12.27.33
I.ROOT-SERVERS.NET.     6D IN A         192.36.148.17
E.ROOT-SERVERS.NET.     6D IN A         192.203.230.10
D.ROOT-SERVERS.NET.     6D IN A         128.8.10.90

;; Total query time: 313 msec
;; FROM: nodens.uraeus.com to SERVER: a.ROOT-SERVERS.NET  198.41.0.4
;; WHEN: Fri Aug  4 10:06:31 2000
;; MSG SIZE  sent: 17  rcvd: 436