If you install .net 2.0 before you install IIS6 then you will not be able to see .net 2 in the allowed extensions list because it needs to register with IIS. Here’s a screenshot where it is missing:
To resolve this, go to the following directory:
c:windowsMicrosoft.NetFrameworkv2.0.50727
Then run this command:
aspnet_regiis.exe –i
Now you can refresh the MMC and enable .net 2.0!