Is the reverse DNS lookup performed by IRC networks usually validated against the forward lookup?

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Google gave me conflicting answers for this one. Some believed that most networks take the lazy attitude to DNS lookups and simply set your hostname to whatever RDNS throws up while others said it was validated bi-directionally.

What, in your experience, is the "standard" procedure?

Elliott

Posted 2012-06-20T21:04:28.257

Reputation: 103

I would guess there is no real standard and it is up to the developer(s) of any given IRC client to decide how lazy they will be. I don't think you're going to get any better an answer than Google provided. In its current form, this is an open-ended/discussion question, which is likely to be closed as SuperUser is intended for questions that have clear, decisive answers. – MaQleod – 2012-06-20T21:09:57.907

I don't agree. I'm requesting an up-to-date generalisation from someone with experience of the major IRC software packages/networks rather than the often outdated answers from sources I have no way of judging the reliability of that I got a lot of on Google. – Elliott – 2012-06-20T21:41:23.817

Why does this matter to you? – Zoredache – 2012-06-20T22:05:25.440

I ask you the same question. Surely the pursuit of knowledge needs no justification. Though in this case, I asked because I have a two-way PTR/A record link and I wanted to find out if I could point the A record somewhere that was more useful (i.e. my server which actually answers HTTP requests) as opposed to my static IP which doesn't really do anything. – Elliott – 2012-06-27T15:40:24.997

Answers

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Yes, it's validated both ways, although there are some older IRCD versions which did not do this. The lazy attitude didn't work very well for IRC servers because people could easily provide a rDNS pointing to a hostname they didn't control. Since vanity hosts are popular, if this wasn't done, we'd see everybody connecting with hosts like "lulz.i.own.microsoft.com".

Further, some IRCDs will reveal the actual IP in whois as well as the resolved as a counter to short TTL times and forward DNS entries being removed shortly after connection.

Stephanie

Posted 2012-06-20T21:04:28.257

Reputation: 1 778

I was under the impression that the PTR record was the hard part to come by as it was for me (and therefore the forward record wouldn't matter so much) which was what got me asking in the first place. This answers my question though! Thanks :) – Elliott – 2012-06-27T15:42:58.110

If the network supports IPv6, it is now trivial to get rDNS thanks to http://6to4.nro.net, and with the abundance of addresses you can afford how many stupid vanity hosts you want. Which may be why some networks don't like ipv6 too much :)

– b0fh – 2012-07-03T05:42:08.920

@b0fh I can't upvote but thanks for the extra info :) – Elliott – 2012-07-10T02:11:44.090