DNS, Downtime & backups
 

My question is,

can I set dns info to 2 separate name servers on 2 different hosts?

example

ns1.hostA.com
ns2.hostA.com
ns1.hostB.com
ns2.hostB.com

what I'd like to accomplish is have my domain automatically point to a backup copy of my site if hostA is having downtime.. Is this possible?

yes

You already have 2 DNS servers in case one is having problems. Now, yet setup multiple A records to point to multiple servers. DNS should not be used for fault tolerance, and is only marginal for load balancing.

This is not the correct solution to the problem you're trying to solve.. but it does provide SOME protection.

SpaceDog,

I agree with Adultwire...

The goal of having a completely redundant website in a second location cannot be solved simply by DNS configuration.

You'd most likely need to find a new DNS solution that will track the state of both hosts and return the IP of the host that's alive. F5 Systems has a product called 3DNS that will most likely do that. They are not cheap solutions.

http://www.f5.com/f5products/3dns/index.html

You'll need two of those... It's not the cheapest way to solve the problem, but it's a pretty damn good one.

Good luck.

-KC

Adult Wire is correct.

The only way to truly provide redundancy like you are talking about is through "Global Load Balancing" and this requires some heavy duty hardware and at least two separate data centers for your sites.

Your money is usually better spent using a host that has true redundancy built into their center so that you don't feel the effects of an outage. Yes, NationalNet is one of these hosts....but there are a couple of others, as well. (wanted to answer your question without being too "spammy" :)


--T

there are ways to fix it, even with one dns :winkwink:

Make sure you have an ISP with redundant hosting....that solves line problems....their routers and switches also need to be redundant for that.

Then have 2 servers with the same site....have both machines
watch eachother to see if they are up....assign both machines
with eachothers IP addresses....of course only 1 ip needs to be
up at the same time.....when your watchdog reports a machine down, have a script take over the main IP (that is in your DNS)

Better would even be to use round robin DNS so you have loadbalacing between both servers. In case 1 goes down the
other takes over the IP from the machine so both "sites" seem
live...

After reboot the second machine comes up with save IP....watchdog on other machine spots other server up again.
triggers script to shut 1 ip down again and second machine boots that IP up again and everything is back to normal.......

I use this setup and it works very well......and it's a LOT cheaper then using services like Akamai who charge you 1500 dollars per Mbit...

I hope this makes sense and is of any help

DynaMite :2 cents:

thanks for the help guys..
Looks like I have some reading to do on this subject.. I'll check out all the suggestions..

spacedogs not the sharpest knife in the drawer. that has already been proven threefold =-)