https://support.microsoft.com/en-us/help/4493730/servicing-stack-update-for-windows-server-2008-sp2 > After you install a servicing stack update together with other updates, a restart may be required to complete the installation.
https://support.microsoft.com/en-us/help/4493471 > Before installing this update > Microsoft strongly recommends you install the latest servicing stack update (SSU) for your operating system before installing the latest Rollup.