Feature Request: DNSRCH option toggle

RouterOS General
1

Are we able to get access to the DNSRCH toggle in the mikrotik DNS cache?

We have a domain setup on our local DHCP server and this has caused some issues wherein DNS lookups passing to domains like example.com will recursively lookup example.com..com.au and then example.com.com.au, then caching the NXDOMAIN response for the TTL time set on the mikrotik. I understand that the value on the mikrotik can be changed but simply setting it to 1minute or similar removes the whole point of having a local caching DNS server.

http://hissohathair.blogspot.com/2009/04/welcome-to-aszcomau-or-resolver-library.html - this is an old blogpost I discovered that explains a little bit more about the issues that are similar to what I am seeing.

http://www.manpagez.com/man/3/resolver/


RES_DNSRCH If this option is set, res_search() will search for host
names in the current domain and in parent domains; see
hostname(7). This is used by the standard host lookup
routine gethostbyname(3). This option is enabled by
default.

2

Are you saying this is a problem when actually using RouterOS to resolve the hostname? Typically the client performing the lookup is where this option is used … not the DNS cache. If you are using :resolve on the mikrotik and it’s an issue then yes, but if it’s your Windows or *nix box generating the queries then thats where you need to fix it.

3

If it’s not the Mikrotik doing it then at very least the option to modify the TTL for NXDOMAIN responses would be a requirement.

Standard TTL set on RouterOS is 1 week, you can modify this but it then affects everything that is cached and thus those resolutions that failed and attempted to try the non existent parent domain lookups will cache as well.