CRL warning while installing Exchange 2010 SP2 rollup

Today I was working with one of our clients , we were installing Exchange 2010 SP2 rollup when the following popup appeared.

This popup indicates that the server cannot connect to the software package publisher ( Microsoft in our case ) to validate Certificate Revocation List ( CRL ) , which maybe due to lack of internet connection – which was our case - or issues with name resolution for Microsoft’s CRL [ crl.microsoft.com ]

In order to overcome this warning you may do one of the following :

1. Ensure that the server is connected to the internet and that “crl.microsoft.com” is resolvable using NSlookup  ( If you got the warning while having internet connection )
2. If your server have no internet access , you can disable checking for publisher’s certificate revocation via Internet Explorer options ( see below )

After disabling CRL publisher checking we were able to proceed with Exchange 2010 rollup installation and without getting any CRL warning window. Once rollup was installed , we reverted back  CRL checking settings from IE options .