Paul Gregg

Jack of all Tech.

Menshn DNS is a (technical thingy).

Written By: pgregg - Jul• 10•2012

So Menshn changed their DNS and stopped their site working for a number of users.

Users pointed it out and Menshn did what Menshn does and blamed everyone else but themselves. I call it the Apple Defence. Or #You’reHoldingItWrong.

What Louise probably doesn’t know is that whoever is advising her*, plainly doesn’t know the first, or last, thing about DNS.

*assuming she has an advisor, perhaps Bozier, as no geek worth his (or her) salt will ever say “technical thingy”.

No Louise, DNS migration does not take 24 hours. It is not the fault of the other ISPs. It is your own fault.

Now Louise and Bozier have both blocked me on twitter, but I’m a magnanimous chap – in the words of Sid [Ice Age] “I’m too lazy to hold a grudge” – so I’ll tell them how to fix it next time.

DNS records have this little number attached to them called a TTL – or Time To Live. Normally the domain TTL is 86400 seconds, or, as you’ve found, 24 hours. This number is entirely within your control. It is the number *you* give to other ISPs when they ask for your zone information. So when their systems receive that data, they can, rightly, assume that the data is good for the next 24 hours.

Thus, when you are planning a domain/DNS change – what do you do? You lower the number to an acceptable outage window, e.g. 60 seconds on your original DNS zone(s) servers. Further, you need to do this at least 24 hours in advance of the change to allow the existing longer TTL records out there to expire.

Thus when you switch DNS servers, or server IPs, your maximum outage window is the new lower TTL.

Welcome to the Internet. It’s a technical thingy.

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