Avi

I have 2 web servers, both running an identical app. I have a link on the homepage that points to http://server2 and a link in everyone's start menu that points to http://server1

Looking at the logs, server1 is hardly being used

Can anyone suggest a simple bit of code that will randomise which server they are directed when they click the link on the homepage?

Thanks

Avi

David_Wallis

create a dns entry called app for example with ip of server 1
then do the same entry but with the ip of server 2

It should then round robin load balance, just depends whether you need to maintain session state and support ssl.

David

Avi

David

Good idea, but it doesn't seem to load balance, will it only use the secondary address if it can't resolve the first one?

stevem2k

Apache or IIS(spit)

RichB

<a href="http://server<?php echo rand(1,2);?>"/>To our home page</a>

As a crude solution.

David - Does that actually work? - Can you have multiple www CNAMEs with different IP addresses OR do you have to have one CNAME called www - pointing at the domain and then create multiple A records with different IP addresses?

RichB

surely it will do a DNS request and then if it can't get to the server it resolved to it would fail rather than looking up again...
I could understand that 10 requests might yield different servers IPs as per the list of A records but not act in a 'redundancy' type manner.

David_Wallis

I never said use a cname

But theres no reason why you cant use an A record for the virtual / internal name.

Do a nslookup on the host and just keep running it and they should swap (or rotate like round robin style )

David_Wallis

RichB

Load Balancing doesnt mean redundancy, he never asked for redundancy!

RichB

Yes I relised that - having reread I see what you mean

David_Wallis

judgejules

If you're using MS DNS Server then tick in "Enable round robin" under the advanced tab of the properties window for the server. Otherwise adding two records of the same type wont make any difference.

Jules

Avi

Ok guys, i have decided to use asp to randomise the server selection which looks like it will work quite well

<%
Dim r

Call Randomize()
r = Rnd()

If (r <= 0.5) Then
Response.Redirect "http://pacsweb2/amI/html"
Else
Response.Redirect "http://pacsweb1/amI/html"
End If
%>

Thanks for your help with this.

Avi

stevem2k

if you are on a M$ environment why not use WLBS ?

David_Wallis

If using AD then enable round robin should be enabled by default

PS to do it right click the server in DNS mmc and do properties.

David