DNS cache issue

DejaVu · July 19, 2020, 9:04pm

Expected Behaviour:

Enabling/Disabling pihole, changing settings, rebooting the system, Black/Whitelisting,
and updating gravity lists all will clear the cached DNS entries.

Actual Behaviour:

DNS cache is being cleared!

Debug Token:

https://tricorder.pi-hole.net/cfahm1i63l

DanSchaper · July 19, 2020, 9:26pm

What is leading you to believe that the Pi-hole FTL cache is not being cleared?

DejaVu · July 20, 2020, 2:01am

I do not have technical knowledge about Pi-hole FTL, so I do not know if it's normal behavior to clear the cache every time I disable/enable the pihole... for me it sounds weird that the cache is cleared for any changes are made on the system... in this way, it is almost useless idea of DNS caching since it will reset on every gravity update..

jfb · July 20, 2020, 2:17am

From your post it's not clear what behavior you expect and what you are seeing. Please clarify.

DejaVu · July 20, 2020, 2:40am

Is it normal that the DNS cache are zeroed when i enable/disable the pihole? Or when update the gravity lists?

yubiuser · July 20, 2020, 6:59pm

Yes it's normal.

Gravity triggers

github.com/pi-hole/pi-hole

gravity.sh

56cd7c4d5


      
          update_gravity_timestamp
          
          # Ensure proper permissions are set for the database
          chown pihole:pihole "${gravityDBfile}"
          chmod g+w "${piholeDir}" "${gravityDBfile}"
          
          # Compute numbers to be displayed
          gravity_ShowCount
          
          # Determine if DNS has been restarted by this instance of gravity
          if [[ -z "${dnsWasOffline:-}" ]]; then
            "${PIHOLE_COMMAND}" restartdns reload
          fi
          
          gravity_Cleanup
          echo ""
          
          "${PIHOLE_COMMAND}" status

Enable triggers

github.com/pi-hole/pi-hole

pihole

56cd7c4d5


      
                echo -e "  ${INFO} Blocking already enabled, nothing to do"
                exit 0
              fi
              echo -e "  ${INFO} Enabling blocking"
              local str="Pi-hole Enabled"
          
              sed -i "/BLOCKING_ENABLED=/d" "${setupVars}"
              echo "BLOCKING_ENABLED=true" >> "${setupVars}"
            fi
          
            restartDNS reload
          
            echo -e "${OVER}  ${TICK} ${str}"
          }
          
          piholeLogging() {
            shift
            if [[ "${1}" == "-h" ]] || [[ "${1}" == "--help" ]]; then
              echo "Usage: pihole logging [options]
          Example: 'pihole logging on'
          Specify whether the Pi-hole log should be used

Which means:

github.com/pi-hole/pi-hole

pihole

56cd7c4d5


      
          svcOption="${1:-restart}"
          
          # Determine if we should reload or restart
          if [[ "${svcOption}" =~ "reload-lists" ]]; then
            # Reloading of the lists has been requested
            # Note: This will NOT re-read any *.conf files
            # Note 2: We cannot use killall here as it does
            #         not know about real-time signals
            svc="kill -SIGRTMIN $(pidof ${resolver})"
            str="Reloading DNS lists"
          elif [[ "${svcOption}" =~ "reload" ]]; then
            # Reloading of the DNS cache has been requested
            # Note: This will NOT re-read any *.conf files
            svc="killall -s SIGHUP ${resolver}"
            str="Flushing DNS cache"
          else
            # A full restart has been requested
            svc="service ${resolver} restart"
            str="Restarting DNS server"
          fi

github.com/pi-hole/pi-hole

manpages/pihole.8

56cd7c4d5


      
                #m                Disable Pi-hole functionality for # minute(s)
          .br
          
          \fBrestartdns\fR [options]
          .br
              Full restart Pi-hole subsystems. Without any options (see below) a full restart causes config file parsing and history re-reading
          .br
          
              (restart options):
          .br
                reload            Updates the lists (incl. HOSTS files) and flushes DNS cache. Does not reparse config files
          .br
                reload-lists      Updates the lists (excl. HOSTS files) WITHOUT flushing the DNS cache. Does not reparse config files
          .br
          
          \fBcheckout\fR [repo] [branch]
          .br
              Switch Pi-hole subsystems to a different GitHub branch
          .br
          
              (repo options):

They question is: Does it really need to a reload,which flushes the cache, or would a reload-lists be sufficient?

DejaVu · July 21, 2020, 11:55pm

Thank you, you have concluded what I wanted to say!

yubiuser · July 22, 2020, 7:20am

@Developers

Do we really need a reload instead of reload-lists after each gravity run and after dis/enabling pihole?

system · August 12, 2020, 7:20am

This topic was automatically closed 21 days after the last reply. New replies are no longer allowed.