How to avoid down time

Let’s face it, all web sites go down from time to time.

Here are a few things you can do - no matter how large or small your sites are - to limit your down time and even avoid it completely.

Diverse DNS

Point your domains to DNS servers hosted in different data centers. Then, if one data center goes down for some reason, the internet will still see the DNS records for your domains by doing lookups on your DNS server in a second location.

To set this up, you can use a DNS service company as your DNS, or if you already host sites in two different data centers, you can just set it up yourself.

If you set it up yourself, make sure you do all your DNS record changes on your primary server and just configure your secondary to do zone transfers from the primary.

Once you set up diverse DNS servers, if your primary site goes down for an extended period, you could modify the records on your secondary DNS server to point to an IP at your secondary location and show a page with a “be back soon” message so that your visitors know that you are experiencing problems and perhaps they will return to your site again later.

Dual homed hosting - simple

If you have your own DNS set up in two data centers, then setting up dual homed hosting is easy. All you need to do is configure your DNS to advertise two A records for your domain, one in the first data center and one in the second data center.

Next, use rsync (or another data sync tool of your choice) and mirror your web site data between location one and location two.

Then, if data center one goes down, your DNS is still being advertised from the second location and your DNS records show a valid IP that is online at the second location.

Dual homed hosting - advanced

You could get more advanced with this and have your secondary DNS retract the DNS advertisements if your primary data center goes down only advertise the IP’s at the secondary location. We’ll cover this in more detail in another post.