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DNS records, CNAMES and Weight

Here is what I am trying to figure out...

Let's say I have to servers SERVER 1 and SERVER 2

I want to be able to access always SERVER1 when typing http://webserver BUT if the server goes down I would like to be able to access SERVER 2 typing http://webserver.

I can't use NLB since is not supported by the app. so I am trying to figure out other ways to do it. I though about CNAMES and DNS records weights.
I don't want the CNAME (http://webserver) to go to SERVER2 when SERVER1 is up and working. I would like people to go SERVER 2 when typing http://webserver when SERVER1 is down.

Any ideas?

BBRazz

There isn't a way to do it with DNS. You need some form of load balancer?

Maybe a VMWARE App or an appliance to sit in front of the servers?

-BBRazz

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Chris Dent

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Chris Dent

I forgot to define Round Robin, I had meant to.

Round Robin attempts to provide a very basic form of load balancing by rotating the order of responses to a requesting client.

e.g.

Query 1

www IN A 1.2.3.4
www IN A 1.2.3.5

Query 2

www IN A 1.2.3.5
www IN A 1.2.3.4

And so on.

Remember that DNS couldn't care less if the target service is up or not, so this Load Balancing will continue even if one of the target systems fails completely.

Chris

llarava

ASKER

Chris-Dent:

If I configure Microsoft NLB between these two servers. If server 1 is dead will server 2 respond. So in other words my users are not going to be sent to the server that is dead?

I am talking about NLB for an IIS Front-End server.

Chris Dent

If you're using NLB then the IP is shared between the servers. Should one fail it shifts onto the remaining node. Because of that, anyone access the service will only access the active server.

There are many different NLB providers if MS isn't suitable. Of course, the more capable it is generally the more it'll cost you.

Chris

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tymes

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