Slow DNS queries

RouterOS General
1

I have sometimes slow dns queries. On my RB1100AHx4. And I must flush cache. Then it si work for day or two.


I have max .concurrent queries 100
max. concurrent TCP sessinos 20
Cache size 2048

Where do I look for the problem?

2
  1. You can try to choose the best servers for forwarding with this - Domain Name Speed Benchmark
  2. My settings on one of my routers look like this
/ip dns set allow-remote-requests=yes cache-max-ttl=6h max-concurrent-queries=500 max-concurrent-tcp-sessions=100 servers=9.9.9.9,149.112.112.112,2620:fe::fe,2620:fe::9
3

Hello!
I had same problem.
These actions helped:

  1. Full update to latest firmware.
  2. Full settings reset to default.
  3. Full router reconfiguring.
  4. NEVER UPDATE ROUTER AGAIN BECAUSE IF YOU UPDATE FIRMWARE YOU HAVE TO FULL RESET AGAIN, IF YOU DO NOT DO THIS YOU GET SLOW DNS AGAIN AFTER UPDATE.

This what happened to me.

Hope this helps. I do not know why this helps but these actions help on hAP ac2 with latest (stable) firmware by date of this my post 16.03.2025.

4

Not of real help, as this issue seems to be somehow DNS cache related; but it general a nice tool to find the fastest DNS near you: https://dnsspeedtest.online/