I have looked through the documentation, but am having trouble locating the place to define DNS servers within NSM 188.8.131.52, specifically to enable GTI File Reputation. As per the File Reputation screen, "Note: GTI queries are performed using standard DNS calls (the hash is embedded in the DNS request). There is therefore no need for direct Internet connectivity from the IPS Sensor to use this feature, but it must have DNS servers defined." I'm looking for where these DNS servers are defined. Thanks for the help!
Go to Devices, then Global, then Name Resolution. You can set the DNS servers globally there. Or if you only want to set them on a few devices, then obviously go select your device, then Setup > Name Resolution.