Question about this site web.da-us.citibank.com with ttl = 0
Mark Andrews
Mark_Andrews at isc.org
Tue Mar 28 23:37:07 UTC 2006
> Is AAAA record mandatory?
No. But consistantly responding to queries other than A queries
is. RFC 1034 / RFC 1035 describe how to respond to queries for
types you don't know about or don't have. RFC 1034 / RFC 1035
are the base DNS specifications. There is no justifiable reason
for any DNS server to get this wrong.
The nameserver for web.da-us.citibank.com is not RFC 1034 / RFC 1035
compliant.
> How does it cause problem like I described?
This will cause the server to be marked as lame.
dig aaaa web.da-us.citibank.com @3dns-c.citibankonline.com +norec
; <<>> DiG 9.3.2 <<>> aaaa web.da-us.citibank.com @3dns-c.citibankonline.com +norec
; (1 server found)
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 4624
;; flags: qr ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;web.da-us.citibank.com. IN AAAA
;; Query time: 245 msec
;; SERVER: 192.193.183.40#53(192.193.183.40)
;; WHEN: Wed Mar 29 10:24:29 2006
;; MSG SIZE rcvd: 40
As will this.
; <<>> DiG 9.3.2 <<>> txt web.da-us.citibank.com @3dns-c.citibankonline.com +norec
; (1 server found)
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 60858
;; flags: qr ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;web.da-us.citibank.com. IN TXT
;; Query time: 249 msec
;; SERVER: 192.193.183.40#53(192.193.183.40)
;; WHEN: Wed Mar 29 10:27:08 2006
;; MSG SIZE rcvd: 40
; <<>> DiG 9.3.2 <<>> a web.da-us.citibank.com @3dns-c.citibankonline.com +norec
; (1 server found)
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49960
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;web.da-us.citibank.com. IN A
;; ANSWER SECTION:
web.da-us.citibank.com. 0 IN A 192.193.187.60
;; Query time: 241 msec
;; SERVER: 192.193.183.40#53(192.193.183.40)
;; WHEN: Wed Mar 29 10:36:01 2006
;; MSG SIZE rcvd: 56
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews at isc.org
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