I'm found the problem. It turns out that 28 days ago I modified my 36arn public zone file (I use a split horizon DNS) and it turns out that there was an error in it. This prevented it from loading, and rightly prevented my secondary DNS from transferring the update. Anyway, after 28 days my secondary DNS rightly stopped serving out IP addresses for the 36arn.co.uk domain (because its cached version was past the expiry time), and at that point everything fell to pieces.

The daft thing is, I can't see what was actually wrong with the zone file. I deleted the record that I appeared to have added (which was an IPv6 AAAA record, and looked OK), updated the timestamp/uid, and everything is now working fine.

Thanks guys for alerting me to this. I think emails had just started bouncing, so much longer and my (non-paying) customers would have started complaining.

behun, I presume you are online on your own system now, in order to send the above message. Sounds like your router was offline for a while, maybe upgrading itself?

Rod, you asked for it...

DNS (Domain Name System) is what turns names (wcg.36arn.co.uk) into numbers (82.69.195.166). Most small setups have a primary (master) DNS server and a slave (backup). Although both of them answer queries to turn names into numbers, the slave will periodically ask the master for the latest update of the records. All records in DNS have a "Time to Live" (TTL). Typically this is 24 hours (but in my case it's 4 hours). In addition, the slave DNS server has an expiry TTL for information it has received from the master.... if it can't contact the master for a certain period of time (in my case, 28 days) it decides that it can no longer trust the information it has, so rather than potentially giving out wrong answers, it goes incommunicado.

I had broken my master DNS on the 2nd of March, but no one (including me) noticed until the slave stopped acting as a backup at about 9am this morning (28 days after the last successful refresh of its information), and over the course of the following 4 hours my entire 36arn.co.uk disappeared off the Internet, including email and website.

Hope that makes sense. It's quite easy really

Don't give up the day job Darkmatter!

It was a complete mystery as to why everything stopped working, not helped by the fact that I was at work and had just come back from the pub! I blame the Shropshire Lad. My server is under my desk at home, and like you it started as a bit of fun to make the Internet go better. I now host a number of small websites and email for several domains, so I have to make sure it keeps going. Hence, the backup DNS and store/forward email in a data centre in France somewhere. I use split horizon DNS... in other words, my DNS server gives different answers depending on whether the query is from the LAN or from the Internet, and the LAN part was working fine. Oh well, I'll know how to spot it next time, and at least I've worked out how I broke the BIND zone file too.

ps. for Rod's benefit, BIND is the "Berkeley Internet Name Daemon" (I think) and is the defacto standard Unix DNS server.

Good morning everyone.

If you can jailbreak an iPhone Rod you can get to grips with DNS, I assure you. It's ancient in technology terms, and hasn't changed much in about 30 years.

On a WCG note, I notice from my stats that hours/result is going up (for a couple of reasons I guess) but the points/hour remains pretty consistent, which is good I think.