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I am looking for information on some of the limits (hard-coded or theoretical) for IIS7 and NLB for website hosting. I have looked around but haven't found anything concrete yet.

On a basic, single server IIS7 setup (Server 2008 x64), is there a limit on how many websites you can host on a single server? Or a theoretical limit on concurrent web requests? I'm not talking about memory limits or resource utilization, I simply mean is IIS7 either hard-coded or limited config-wise to only support a maximum number of websites? 1,000? 10,000? More?

Also, does adding a second server via Microsoft's NLB into the mix reduce any of these theoretical limits?

I will be looking into capacity planning and resource limits later, but for right now I was just trying to find any documentation on what the theoretical limits are of IIS7 itself.


Update: Just saw this blog post with some info on IIS6. If anyone knows if these limits and/or server tweaks still exist for 2008/IIS7, please let me know.

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up vote 1 down vote accepted

According to David Wang on the Microsoft IIS team, there are no limits to the number of websites supported by IIS (see post here) other than hardware limitations. Although that answer related to IIS6, I have to assume it is the same for IIS7.

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Thanks for the link. Funny - I just found a blog post by David Wang as well, and just came back here to update my initial post :) – zona Jul 27 '09 at 22:05
Actually there is a limit; the MaxValue of whatever data type they use to enumerate the websites. – tsilb Aug 2 '09 at 5:51

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