DNS Outages - Setup Reliable DNS

Question

I run a VPS out of a hosting provider in Amsterdam, my potential users are mainly located in London. In the last 90 days I have had 3 instances of my users not being able to access the site though the servers were up and running (checked by logging into the servers using SSH). On investigation I found that the DNS' were down and hence the URL's were not being resolved. However the perception in the users mind is that the site is down.

I am keen on having a more reliable DNS and have researched the following options

1. Transfer the domain to another hosting provider who is more reliable
2. Change the NS entries for the domain to point to the hosting company's name space servers
3. Change the NS entries for the domain to point to a private name space servers provider
4. Use a commercial CDN and hence their name space servers.

Option 4 has been ruled out because we plan to implement Varnish as our web cache. I haven't been able to locate information on the pro's and cons of the first three options even after hours of googling.

Would like to hear from someone on the most feasible method to have a reliable DNS'

Answer 1

You've kind of overlooked option 5, which is to add another DNS server at a different provider.

You don't tell us the domain name in question, so we can't check the whois, but I'm guessing that either your current DNS provider uses two servers at the same facility, or that they only actually use one server.

The DNS is designed to be highly-available, but both the above schemes subvert the main mechanism by which this is designed to happen: multiple DNS servers at multiple diversely-connected providers.

You may find that this is less effort than any of the first three suggestions above: rent or build yourself a DNS server on a VPS with a completely different provider, configure your current server(s) to allow the zone transfers, add it to your NS records and the whois through your registrar, and you're done.

Edit: the .co.uk is with a provider that seems to do it properly; doing a dig on the nameservers in the whois gives me 212.67.202.2 and 92.51.159.40, which are very likely two completely different servers at different locations (traceroute adds confirming evidence, suggesting they are in different countries). I'd be very surprised if they were both unavailable at the same time. You are likely to add little redundancy to your setup by adding a third server under your own control, though you will have more insight into why that one's down, if it goes down.

The .biz, however, is not so well-done. The servers seems to be 64.92.114.5 and 64.92.115.5. Whilst those are nominally separate, it's likely that they're on the same internet pipe (again, traceroute suggests this also), and they may simply be two different addresses on the same machine (we can't know this from outside). Replacing one of the existing ones with a server under your control would increase redundancy.

Answer 2

If you are running the DNS yourself, you need multiple nameservers spread out across multiple locations. This is a lot of work and more expensive if your needs aren't extraordinary.

Otherwise, I recommend you use a third party to host your domain name. If the one you're using now isn't sufficient, try another. Amazon does it for cheap (under the product name Route 53), or you can use NameCheap's free DNS hosting, or I've also heard good things about DNS Made Easy (.com).