Apologies if this has already been covered:
Our network now has two gateways to different ISPs - if I add a static route with gateway=x.x.x.x,y.y.y.y PPPoE clients will not pick up the other ISP’s DNS addresses.
I couldn’t find anything about this in the manual…
Trisc
I suppose in this case you should use the internal DNS cache of MikroTik and let your users use this as their DNS server…
Would that work for PPPoE connections?
Or if I set primary DNS server from ISP 1 and secondary DNS server from ISP 2 - would I be taking a risk only having 1 DNS server per ISP?
Come to think of it we have a linux router that allows unlimited DNS nameserver entries. Can MT not do the same?
Trisc
It is usually better to run your own DNS servers. The purpose of DNS is to convert url names to ip addresses. The faster this is done, the faster the link to the address is made and the web page loads. If the DNS servers are on your network, this happens much faster. If one of the upstream servers goes down for some reason, then you experience significant delays.
I’m aware of what nameservers do but I’m not willing to invest and maintain my own. That’s what we pay the ISP to do.
Trisc
I would suggest you try using the MT box as your DNS server. Under IP-DNS, enter the addresses of the two DNS boxes to use. Enable the option to allow remote requests. This way your clients only need one DNS address. They query the MT box and it querys the DNS servers. It returns the data and stores it in the cache. Try this and see if it solves your PPPOE connection problem.
OK - this is a Routerboard handling a lot of PPPoE connections - would there be sufficient RAM for a DNS cache? What happens when the cache is full?
Trisc
My DNS cache size is limited to 2mb, but rarely goes over 250k. The entries are deleted after their expire time is reached, the longest is usually 72 hours. I would imagine if the cache fills up, the oldest entries are dropped to make way for the new ones.