Hi Stuart,

I ran into an issue similar to what you're describing. We have 5000+ devices and some of them would sporadically report down (dns) then come back on the next poll. DNS was not the culprit, well, not directly. We run Ubuntu and we found out that the default local DNS cache daemon (systemd-resolved) had issues (besides being limited to a static value of 4096 entries) We replaced the host's local cache with bind (very simple to set up) and haven't had any similar issue since.

If you indeed run a local DNS cache, you can try disabling it altogether and see if things get better.

HTH,

Ahmed.

Le ven. 18 juin 2021, à 02 h 19, Mills, Stuart via observium < observium@observium.org> a écrit :

Hi,

Every now and again I have an issue with Observium as it will read devices offline and show down (DNS) however when I restart Observium devices come back. I have run DCDIAG, and DNS is working ok, can anyone shed any light on this issue?

-- Kind Regards

*Stuart J Mills* *Systems Administrator*

*Dresden International School* Annenstr. 9, 01067 Dresden Germany *Phone:* +49(0)351 44007 32 smills@dresden-is.de www.dresden-is.de

*DIS Dresden International School gGmbH* Sitz der Gesellschaft | Company Register: Annenstr. 9, 01067 Dresden Registergericht | Court of registration: Amtsgericht Dresden, HRB 35540 Geschäftsführung | Executive Board: Steven Calland-Scoble, Andrea Harnisch

*DIS Dresden International School gGmbH* Sitz der Gesellschaft | Company Register: Annenstr. 9, 01067 Dresden Registergericht | Court of registration: Amtsgericht Dresden, HRB 35540 Geschäftsführung | Executive Board: Steven Calland-Scoble, Andrea Harnisch

---

observium mailing list observium@observium.org http://postman.memetic.org/cgi-bin/mailman/listinfo/observium