OSEC

Neohapsis is currently accepting applications for employment. For more information, please visit our website www.neohapsis.com or email hr@neohapsis.com
 
Subject: Re: dnscache
From: Brad Knowles (blkskynet.be)
Date: Wed Jun 14 2000 - 09:14:39 CDT

At 12:53 PM +0000 2000/6/14, Ralf Hildebrandt wrote:

> Uh. If I "dig +debug aol.com MX", I get:
>
> ... snip ...
> ;; Total query time: 15 msec
> ;; FROM: gulliver to SERVER: default -- 10.0.0.1
> ;; WHEN: Wed Jun 14 14:52:37 2000
> ;; MSG SIZE sent: 25 rcvd: 471

        Let's show the whole ugly, nasty thing:

$ dig +debug aol.com. mx

; <<>> DiG 8.1 <<>> +debug aol.com. mx
;; res_mkquery(0, aol.com., 1, 15)
;; res options: init debug recurs defnam dnsrch
;; res_send()
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUERY SECTION:
;; aol.com, type = MX, class = IN

;; Querying server (# 1) address = 195.238.2.22
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
;; flags: qr rd ra; QUERY: 1, ANSWER: 10, AUTHORITY: 2, ADDITIONAL: 13
;; QUERY SECTION:
;; aol.com, type = MX, class = IN

;; ANSWER SECTION:
aol.com. 59m21s IN MX 15 yh.mx.aol.com.
aol.com. 59m21s IN MX 15 za.mx.aol.com.
aol.com. 59m21s IN MX 15 zb.mx.aol.com.
aol.com. 59m21s IN MX 15 zc.mx.aol.com.
aol.com. 59m21s IN MX 15 zd.mx.aol.com.
aol.com. 59m21s IN MX 15 yb.mx.aol.com.
aol.com. 59m21s IN MX 15 yc.mx.aol.com.
aol.com. 59m21s IN MX 15 yd.mx.aol.com.
aol.com. 59m21s IN MX 15 ye.mx.aol.com.
aol.com. 59m21s IN MX 15 yg.mx.aol.com.

;; AUTHORITY SECTION:
aol.com. 6m44s IN NS DNS-02.NS.aol.com.
aol.com. 6m44s IN NS DNS-01.NS.aol.com.

;; ADDITIONAL SECTION:
yh.mx.aol.com. 40M IN A 205.188.157.4
yh.mx.aol.com. 40M IN A 205.188.157.5
yh.mx.aol.com. 40M IN A 205.188.157.1
yh.mx.aol.com. 40M IN A 205.188.157.2
yh.mx.aol.com. 40M IN A 205.188.157.3
za.mx.aol.com. 40M IN A 152.163.224.2
za.mx.aol.com. 40M IN A 152.163.224.3
za.mx.aol.com. 40M IN A 152.163.224.4
za.mx.aol.com. 40M IN A 152.163.224.5
za.mx.aol.com. 40M IN A 152.163.224.1
ye.mx.aol.com. 40M IN A 205.188.158.25
DNS-02.NS.aol.com. 1d11h25m22s IN A 205.188.157.232
DNS-01.NS.aol.com. 1d19h42m50s IN A 152.163.159.232

;; Total query time: 2 msec
;; FROM: mercury to SERVER: default -- 195.238.2.22
;; WHEN: Wed Jun 14 15:24:55 2000
;; MSG SIZE sent: 25 rcvd: 471

        Blech. Double blech. Blech, say I.

        Damnit, I fixed this crap years ago, before I left. Now they've
gone back to doing this kind of garbage again.

        Jeezus, you'd think that someone over there would have learned,
after the nineteen hour downtime, when I got personally blamed for
taking down all e-mail for the entire Internet.

        In fact, rightly or wrongly, I think a couple of new MTAs were
born soon after that debacle, in large part because of the extremely
poor behaviour of typical installations of some other common MTAs
under these kinds of circumstances.....

> What is the limit (for the size of an UDP packet) ?

        512 bytes, no more. 

--
   These are my opinions -- not to be taken as official Skynet policy
======================================================================
Brad Knowles, <blkskynet.be>                || Belgacom Skynet SA/NV
Systems Architect, Mail/News/FTP/Proxy Admin || Rue Colonel Bourg, 124
Phone/Fax: +32-2-706.13.11/12.49             || B-1140 Brussels
http://www.skynet.be                         || Belgium