nanog mailing list archives
Re: DNS TTL adherence
From: Rodney Joffe <rjoffe () centergate com>
Date: Wed, 15 Mar 2006 07:16:35 -0700
On Mar 15, 2006, at 1:56 AM, Simon Waters wrote:
In answer to the original question, I'm not aware of any DNS servers that don't expire data at the end of the TTL period correctly. Failing to expire such data would be a good way of breaking things, and people would just notuse such broken software.
Let me help you become aware, then...
I'm not sure why the OP thinks someone would research such a bug in detail, myexperience is they would just fix it.
Some people don't believe it is a bug, and therefor don't see that anything needs "fixing".
Feel free to, for example, send 2 consecutive queries for a record that has a short (<10,000 second TTL) to 212.23.11.206. This is one of the over 100,000 random open recursive servers that have been party to some of the recursive DNS server amplification DDoS attacks over the last few weeks... and this behavior exists in a number of them.
If you can't think of a record to query for that has a short enough TTL, I've created a wildcard entry of:
*.example.centergate.comso that you can test this repeatedly without having to wait for the overridden TTL to expire. Just use a different random wildcard record each time (remembering to send 2 consecutive identical queries to see the misbehavior).
$ dig @212.23.11.206 jhgfd.example.centergate.com a This behavior is unfortunately not unique. /rlj
Current thread:
- DNS TTL adherence Thurman, Steven (Mar 14)
- Re: DNS TTL adherence ennova2005-nanog (Mar 14)
- Re: DNS TTL adherence Joe Maimon (Mar 14)
- Re: DNS TTL adherence Simon Waters (Mar 15)
- Re: DNS TTL adherence Rodney Joffe (Mar 15)
- Re: DNS TTL adherence Simon Waters (Mar 15)
- Re: DNS TTL adherence Jon Lewis (Mar 15)
- Re: DNS TTL adherence Christopher L. Morrow (Mar 15)
- Re: DNS TTL adherence Joe Maimon (Mar 14)
- Re: DNS TTL adherence ennova2005-nanog (Mar 14)
- <Possible follow-ups>
- FW: DNS TTL adherence Thurman, Steven (Mar 15)
- RE: DNS TTL adherence Sharad Agarwal (Mar 15)
- Re: DNS TTL adherence Simon Waters (Mar 16)
- Re: FW: DNS TTL adherence Igor Gashinsky (Mar 17)
- RE: DNS TTL adherence Sharad Agarwal (Mar 15)