This seems like a strange situation. My WISP co-owner uses the default / out-of-the box RouterOS config for client installs and has done so on approximately 200 devices. This seems to work the vast majority of the time but in some cases we may have unpredictable behavior. Clients / customers reporting intermittent connectivity loss and in a few cases, evidence of a DNS resolution problem. Investigation into the potential DNS issues yielded the following.
1 - Most client devices have valid DNS Server settings when connected to the Mikrotik default configured device.
2 - The default RouterOS /ip dhcp-server configuration has no dns server.
Here is a new / out-of-the box HAP AC Lite router w/ the default config:
[admin@MikroTik] /ip dhcp-server network> export
jan/02/1970 00:13:03 by RouterOS 6.45.9
software id = 9PDW-KINW
model = RB952Ui-5ac2nD
serial number = CC3F0CC91E81
/ip dhcp-server network
add address=192.168.88.0/24 comment=defconf gateway=192.168.88.1
Notice, no dns server. My background in networking tells me that should not work, so I have always manually added the dns server setting as either the same as the default gateway (in this case 192.168.88.1) or something upstream like 8.8.8.8 and similar depending on requirements for that customer. But like I said, our WISP co-owner has done 200 or so of these installs w/ out adding the dns server manually and they seem to work mostly, most of the time etc.
So the question arises, why does this default configuration work at all? I've seen discussions on this in Reddit but no good answers? Is there something in RouterOS that issues a DNS server to dhcp clients even when the /ip dhcp-server network dns server option is not set ?
Second, is it possible this is some not-intended-to-be-used functionality which isn't reliable? That would explain why some customers seem to have random dns problems.
Any insight into this behavior would be much appreciated.
Thanks,
-scott