Issue: You need to deploy Exchange 2013 CU21.
Solution: The following step by step instructions will guide you through the Exchange 2013 installation process. This will be a new installation of Exchange 2013 using the CU21 media.
0) If you haven’t already done so, you first need to install the Exchange 2013 pre-requisites and prepare the AD Schema for Exchange 2013 CU21.
1) Download Exchange CU21, here is a convenience link to download the latest version of Exchange 2013.
2) Execute the downloaded CU21 file to extract the installer, choose the path you would like the installation files extracted to, make sure you choose a drive with plenty of free space
The installation files will be extracted:
3) open the folder you extracted the installation files, right click setup.exe and click ‘Run as administrator’.
4) click ‘next’ on the introduction (and review the license agreement).
5) Decide whether you want recommended settings or not for error reporting and usage data gathering:
6) Select the server roles that you desire. Whether you are setting up a single server or multi-server environment, Microsoft Preferred Architecture recommends all roles on each Exchange Server.
7) Choose the installation path for Exchange 2013 CU21 (I generally accept the defaults)
8) Next the readiness checks will commence. On all my CU21 installs I have been getting the error “Setup can’t contact the primary DNS server using TCP port 53”. I subsequently verify DNS functionality and have proceeded with ignoring the error and have not had any problems.
If any errors are encountered during the readiness checks / pre-requisite check then you will need to resolve the issues before continuing. You can use the ‘retry’ button to re-run the readiness checks.
9) Once the readiness checks are complete, proceed with setup. Exchange 2013 CU21 setup will copy files and other setup processes.10) Once setup completes it is recommended that you reboot the Exchange Server.