https://wiki.mikrotik.com/wiki/Advanced ... _Scripting

Which internet hosts do you choose for ping check ??
(often, big companies change ip address or ping policies....resulting unreachable)

Do you experience , sometimes, routes become "unreachable" despite you can ping hosts correctly ?

Google DNS is highly reliable and globally diverse. 8.8.8.8 and 8.8.4.4.

Sent from my Pixel XL using Tapatalk

Since both are already used and I need a pair more (a pair for first wan and a pair for the second one) , what else do you suggest ??

There are several ideas; but the most stable ones that I've used before are: OpenDNS (208.67.222.222 & 208.67.220.220); Level3 (4.2.2.1 & 4.2.2.2) ; Quad9 (9.9.9.9 & 149.112.112.112)