Firewall Wizards mailing list archives

Re: Allowing DNS servers to operate behind NetScreen 500


From: David Lang <david.lang () digitalinsight com>
Date: Mon, 17 Feb 2003 20:56:16 -0800 (PST)

also some large websites don't load balance behind a single IP address,
instead they use lots of IP addresses.

according to the post 9-11 talks from the folks reunning the turner
websites they haven''t found a load balancer they trust to use in their
high-bandwidth environment (>2Gb of internet bandwidth on 9-11 and I think
they mentioned that they are up above 3Gb now) they move servers from one
site to another and change DNS to balance their load below is a list of
the cnn.com servers right now, if something significant ewere to happen
the list would get significantly longer.

David Lang

web:~# dig cnn.com

; <<>> DiG 9.2.1 <<>> cnn.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24772
;; flags: qr rd ra; QUERY: 1, ANSWER: 8, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;cnn.com.                       IN      A

;; ANSWER SECTION:
cnn.com.                115     IN      A       64.236.24.20
cnn.com.                115     IN      A       64.236.24.28
cnn.com.                115     IN      A       64.236.16.20
cnn.com.                115     IN      A       64.236.16.52
cnn.com.                115     IN      A       64.236.16.84
cnn.com.                115     IN      A       64.236.16.116
cnn.com.                115     IN      A       64.236.24.4
cnn.com.                115     IN      A       64.236.24.12

;; Query time: 30 msec
;; SERVER: 64.81.45.2#53(64.81.45.2)
;; WHEN: Mon Feb 17 22:00:27 2003
;; MSG SIZE  rcvd: 153


On Mon, 17 Feb 2003, Chuck Swiger wrote:

Date: Mon, 17 Feb 2003 11:39:57 -0500
From: Chuck Swiger <chuck () codefab com>
To: "'firewall-wizards () honor ics..." <firewall-wizards () honor icsalabs com>
Subject: Re: [fw-wiz] Allowing DNS servers to operate behind NetScreen 500

Reckhard, Tobias wrote:
[ ... ]
I'd be interested in other, real-world reasons why DNS responses
should be allowed to be over 512 bytes in size. Not out of
opposition, but out of interest.

MX records for popular domains:

58-sec% dig aol.com. @pi.codefab.com. mx
; <<>> DiG 8.3 <<>> aol.com. @pi.codefab.com. mx
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 4, ADDITIONAL: 30
;; QUERY SECTION:
;;      aol.com, type = MX, class = IN

;; ANSWER SECTION:
aol.com.                1H IN MX        15 mailin-02.mx.aol.com.
aol.com.                1H IN MX        15 mailin-03.mx.aol.com.
aol.com.                1H IN MX        15 mailin-04.mx.aol.com.
aol.com.                1H IN MX        15 mailin-01.mx.aol.com.

;; AUTHORITY SECTION:
aol.com.                1H IN NS        dns-01.ns.aol.com.
aol.com.                1H IN NS        dns-02.ns.aol.com.
aol.com.                1H IN NS        dns-06.ns.aol.com.
aol.com.                1H IN NS        dns-07.ns.aol.com.

;; ADDITIONAL SECTION:
mailin-02.mx.aol.com.   5M IN A         64.12.136.89
mailin-02.mx.aol.com.   5M IN A         64.12.136.121
mailin-02.mx.aol.com.   5M IN A         64.12.137.89
mailin-02.mx.aol.com.   5M IN A         64.12.137.184
mailin-02.mx.aol.com.   5M IN A         64.12.138.89
mailin-02.mx.aol.com.   5M IN A         64.12.138.120
mailin-03.mx.aol.com.   5M IN A         64.12.136.217
mailin-03.mx.aol.com.   5M IN A         64.12.136.249
mailin-03.mx.aol.com.   5M IN A         64.12.137.121
mailin-03.mx.aol.com.   5M IN A         64.12.137.152
mailin-03.mx.aol.com.   5M IN A         64.12.138.57
mailin-03.mx.aol.com.   5M IN A         64.12.138.120
mailin-04.mx.aol.com.   5M IN A         152.163.224.122
mailin-04.mx.aol.com.   5M IN A         64.12.136.153
mailin-04.mx.aol.com.   5M IN A         64.12.137.121
mailin-04.mx.aol.com.   5M IN A         64.12.137.152
mailin-04.mx.aol.com.   5M IN A         64.12.138.89
mailin-04.mx.aol.com.   5M IN A         205.188.156.154
mailin-04.mx.aol.com.   5M IN A         64.12.138.152
mailin-01.mx.aol.com.   5M IN A         152.163.224.26
mailin-01.mx.aol.com.   5M IN A         64.12.136.57
mailin-01.mx.aol.com.   5M IN A         205.188.156.122
mailin-01.mx.aol.com.   5M IN A         64.12.137.89
mailin-01.mx.aol.com.   5M IN A         64.12.137.184
mailin-01.mx.aol.com.   5M IN A         64.12.138.57
mailin-01.mx.aol.com.   5M IN A         64.12.138.152
dns-01.ns.aol.com.      44m44s IN A     152.163.159.232
dns-02.ns.aol.com.      44m44s IN A     205.188.157.232
dns-06.ns.aol.com.      1d16h44m41s IN A  149.174.211.8
dns-07.ns.aol.com.      1d16h44m41s IN A  64.12.51.132

;; Total query time: 222 msec
;; FROM: sec.codefab.com to SERVER: pi.codefab.com.  12.38.161.140
;; WHEN: Sun Feb 16 19:07:29 2003
;; MSG SIZE  sent: 25  rcvd: 699

-Chuck

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