I replaced an old ISA with an RB1200 with the RouterOS 5.5. Aside from a screw-up from my ISP (our fixed external IP that we pay for proved to be less fixed than we paid for 
), everything was fairly smooth sailing.
At least at first… Now I’m experiencing several events where the DNS on the RouterBoard is doing funky stuff with static entries for local servers without public/internet IPs.
- Sometimes it simply doesn’t resolve even though the correct entries are clearly in the static entries or DNS cache. The size is correctly set to 512, the load on the RB is extremely low and there are no firewall rules to explain why this is happening.
- I made a typo when adding a static entry (in the name, not the IP). I quickly corrected it. The entry for it in the DNS cache however failed remained (as well as the new correct entry). Flushing the cache from winbox and from the terminal made no difference. The faulty entry stubbornly remained until I reset the router.
- When connecting over PPTP VPN, failure to resolve DNS seem much more common.
Quite annoying. Tried most steps that appear logical (reboots, double check settings, disable firewall rules, try with several clients,…). Sometimes it simply doesn’t feel like resolving the requests…
Any pointers?