rDNS
The Netsweeper Policy Service feature for Reverse DNS (rDNS) filtering is used to map requests to IP addresses back to the hostname associated with the specific IP address.
Disabling rDNS
rDNS can indeed be disabled. To do this you simply make all lists no longer trigger a hostname resolution.
locallist_rdns_prepopulate none
localcatlist_rdns_prepopulate none
categoryurllist_rdns_prepopulate none
globallist_rdns_prepopulate none
systemprotocollist_rdns_prepopulate none
systemlist_rdns_prepopulate none
masterlist_rdns_prepopulate none
preemptivelist_rdns_prepopulate none
Slowing down rDNS
It would be recommended to keep rDNS enabled, and rather change the resolution rates to a lower level. These entries you can adjust to a much much lower level.
rdns_dnslookup_max_rate 10
rdns_expired_rate 100
Disabling the rDNS Lookup during policy processing
To disable the policy request http://IP or https://IP to check the RDNS cache, you can disable this by using
policy_rdns_lookup_enabled false
It is important to remember, that we will still resolve the hostname entries if only the above setting is changed, but we will not use the cache to perform any IP to hostname lookups.
Additional Information
For a more-detailed overview on how the RDNS works, please see How does the rDNS work when filtering HTTPS in Netsweeper? knowledgebase article
For our rDNS technical configuration guide, please refer to our rDNS Filtering Configuration document.