Please excuse any ignorant use of terminology, I am not a DNS expert like others on here, but I can share some experience in the smaller business world.
A company I worked with a couple of years ago was using Dyn as their DNS provider, and one day we got a notifcation that we had passed the usage limits for our account. This seemed impossible considering our site was getting a couple of hundred unique visitors a day. A few things came out of the analytics.
1) A short TTL on an A record had been left on from a website migration project. The majority of the requests were coming from our internal website administrators. I moved it up to a couple of hours and this went a way.
2) We were getting a huge amount of AAAA record hits. I think most modern browsers/OS try quad A first??? We didn't have IPv6 configured, and therefore the negative resolution had a TTL set to the minimum on the SOA record, which was 1second! A change of this to 60 caused a huge reduction in requests. I suppose I should have set up ipv6, but I didn't.
3) When we sent out stuff to our mailing list the SPF (or rather TXT) records saw a peak that was off the chart. We had a pretty settled infrasructure, so I moved that TTL to a day (I think from memory) and it flattened the peak somewhat.
4) There was a large peak in MX request around 9am. I put this down to people opening their email when they got to work and replying to us. I had to set the TTL to a couple of days (of course) to smooth that one.
I like to think it was worthwhile and improved things for users. I at least had a nice warm glow that I had saved the internet from a bunch of junk requests, and it just felt tidier.
A company I worked with a couple of years ago was using Dyn as their DNS provider, and one day we got a notifcation that we had passed the usage limits for our account. This seemed impossible considering our site was getting a couple of hundred unique visitors a day. A few things came out of the analytics.
1) A short TTL on an A record had been left on from a website migration project. The majority of the requests were coming from our internal website administrators. I moved it up to a couple of hours and this went a way.
2) We were getting a huge amount of AAAA record hits. I think most modern browsers/OS try quad A first??? We didn't have IPv6 configured, and therefore the negative resolution had a TTL set to the minimum on the SOA record, which was 1second! A change of this to 60 caused a huge reduction in requests. I suppose I should have set up ipv6, but I didn't.
3) When we sent out stuff to our mailing list the SPF (or rather TXT) records saw a peak that was off the chart. We had a pretty settled infrasructure, so I moved that TTL to a day (I think from memory) and it flattened the peak somewhat.
4) There was a large peak in MX request around 9am. I put this down to people opening their email when they got to work and replying to us. I had to set the TTL to a couple of days (of course) to smooth that one.
I like to think it was worthwhile and improved things for users. I at least had a nice warm glow that I had saved the internet from a bunch of junk requests, and it just felt tidier.