Your security department wants you to do this to make the server type harder to identify. This may lessen the barrage of automated hacking tools and make it more difficult for people to break into the server.
Within IIS, open the web site properties, then go to the HTTP Headers tab. Most of the X- headers can be found and removed here. This can be done for individual sites, or for the entire server (modify the properties for the Web Sites object in the tree).
For the Server header, on IIS6 you can use Microsoft's URLScan tool to remote that. Port 80 Software also makes a product called ServerMask that will take care of that, and a lot more, for you.
For IIS7 (and higher), you can use the URL Rewrite Module to rewrite the server header or blank it's value. In web.config (at a site or the server as a whole), add this content after the URL Rewrite Module has been installed:
<rewrite>
<outboundRules rewriteBeforeCache="true">
<rule name="Remove Server header">
<match serverVariable="RESPONSE_Server" pattern=".+" />
<action type="Rewrite" value="" />
</rule>
</outboundRules>
</rewrite>
You can put a custom value into the rewrite action if you'd like. This sample sourced from this article which also has other great information.
For the MVC header, in Global.asax:
MvcHandler.DisableMvcResponseHeader = true;
Edited 11-12-2019 to update the IIS7 info since the TechNet blog link was no longer valid.
The IIS logs only record querystring and header information without any POST data.
If you're using IIS7, you can enabled Failed Request Tracing for status code 200. That will record all of the data and you can select which type of data to include.
In either IIS6 or 7, you can use Application_BeginRequest in global.asax and create your own logging of POST data.
Or, in IIS7, you can write a HTTP Module with your own custom logging.
Best Answer
IIS can log few HTTP headers; including Referer, Cookie and User-agent; but not all. If you want to log any of these variables, you'll have to set them up from IIS manager (Web Site Properties > Web Site Tab > Enable Logging > Properties)