No syslog message type is dedicated to be assign under dns category, as if we configure syslog on Netscaler, 2 parameters are compulsory which is Log Facility is defined by RFC 3164 https://www.ietf.org/rfc/rfc3164.txt , aother is format, no other option, then Severity is the thing you want to know like how severe the alarm or message it is, but also is not dns dedicated, which applied on the whole device. So unfortunately, no specific dns log can be done.