cynan wrote:Are you referring to how the DNS server you are connected through routes ISP requests? Or are you referring to the selection of the DNS server by the local router? I know that I get more consistent performance if I turn off dynamic DNS in my router and enter the DNS servers of my ISP directly. How connection requests are routed beyond that is up to my ISP (which usually does a better job than my relatively cheapo router).
I'm not really sure what you mean by all this, but DNS simply like a phone book that associates names with numbers. E.g.I query my DNS server to discover that http://www.netflix.com translates to 18.104.22.168. But, it's even more complex than that, because of anycast (your IP for netflix.com could be different). But we'll keep it simple.
Dynamic DNS in your router probably refers to a dynamic name service like no-ip.biz or dyndns.org, in which you can get a name associated with a non-static IP. It works because the router lets the dynamic name service know when your dynamic IP changes, so they can update the records.
So that shouldn't have any effect on anything, and if you mean that the DNS servers you get through DHCP are somehow different than what you think are your ISP's DNS servers, you'd better have a talk with them because that's really strange.
And yes, once you are past names (and thus DNS) and into the realm of numeric IPs, you have no control of the routing. In fact, at that point, your ISP has very little control of the routing.