www.sub.example.com - how to make this resolve on an IIS server

[tedster]

I am out of my depth here. One of my clients has a magazine associated with their main website, and it sits at sub.example.com. They have found that many people are assuming every address must begin with "www" and so they are entering www.sub.example.com and getting an error message.

So my question is, what must happen so that this address DOES resolve? I know have seen this, but I never thought about making it happen before. The client tried to do it, but only managed to make both urls stop resolving.

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A couple extra details - the domain and subdomain are on a dedicated box running IIS. The 'www' domain has its own IP address and the subdomain also has its own, different IP address. The client owns other, as yet unused, IP addresses -- which I really can't see using for a task that is essentially handling typos, unless an extra IP address is required. There are a few other small websites on the server, all run by the smae client -- some with dedicated IPs and some that share IPs.
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[gpmgroup]

I think you need to do two things.

1) You need to create as "A" record in the DNS for www.sub.example.com

2) In the IIS Manager

Browse down to Websites ¦ example.com
Right click
On the "Web Site" tab select Advanced
In the multiple properties for this website window click "add"
In the add/edit web site identifcitation window set

IP address = "All unassigned"
TCP Port = 80
Host Header value = www.sub.example.com
Click OK
Click OK

THEN try www.sub.example.com in your browser If you try it before the "unable to resolve bit" may be cached somewhere enroute to the browser.

btw example.com www.example.com sub.example.com and www.sub.example.com can all be on the same IP without issue.

[tedster]

Thanks gpmgroup - that clarifies things nicely.