This one is a quite the quibble because I got sick and tired of some spam coming in on my Barracuda Spam Filter (beautiful spam filter by the way) and so I figured that I might as well get rid of them the old fashioned way by deleting the MX records.
It used to work that changes to the MX (mail exchange server) record in a zone file, it would pretty much update within a couple hours if not immediately. At least, this is the way that it used to be back in the day with the internet was a new-fangled thing and everyone was doing everything they could to make what is behind the scenes, a scary array of skips jumps and hops to connect, work as best as it could. But, I went ahead and got rid of these records. One would think that in doing this, it would cut off the link for spammers (or anyone for that matter) to send mail to this server. As it happened, this didn’t work. Crap is still filtering through to it and I deleted the MX record three weeks ago!
Thinking that there was something else at work, I tried this approach in a modified way with two other domains I wanted to cut off, but instead of just dumping the MX, I substituted in one that was completely bogus. Well, I did that yesterday and I am still getting junk on the server.
It was all starting to blow my mind a bit or really worry about the internet in general, until I saw this article on Slashdot about how some service providers are ignoring TTL in the DNS zone files. In other words, the bit that tells when the files needs to be updated is being ignored and updates are not taking place and being seeded across the network in a timely fashion.
I’m not sure what the end result will be in my little experiment, but it seems that at first, zone files are being ignored altogether and that updates are nearly not happening at all. While it used to take awhile to get updates across the globe, they would happen within a week usually, but what I’m seeing here is showing that something larger is going on. I know that there are problems with the DNS pools out there being contaminated and maybe that’s why TTL is being mucked with right now, but it would seem to point to a larger epidemic and show that there is something symptomatically wrong with the Net these days and yes, I checked the TTL settings, which are set to two hours on these domains. I’ll keep an eye on this…