I know it is posible to have a floating static route. what i want to do is set up a floating static route to use cox when verizon goes down. now with my router being my dhcp server and dns server, can i add the cox dns address to the router as well as verizons?
Yes but be aware that might well mean your clients use the cox DNS server even when the verizon connection is up and running. Shouldn't matter too much.
** Edit - unless verizon are filtering DNS requests and only allow DNS requests from you to go to their DNS servers in which case that could cause problems.
is there a way you can set it up so the snd request go down the line of dns servers starting with verizon and if no responce it will go to the cox dns?
Not sure but it could still be a problem even if you could ie. you specifiy verizon first and the cox one second. If the verizon connection went down you could then find clients have to timeout waiting for no response from the verizon DNS server before it then went on to the cox DNS server.
So forcing an order in the DNS servers may not help. It really depends on whether your ISPs filter DNS messages. I don't know whether they would do this sort of thing but i suspect they don't so i think you will be okay.
Alternatively you could use public DNS servers eg. google which would remove the possible timeout issue when one connection goes down.
If you're using 4.2.2.1 and 4.2.2.2, Verizon doesn't filter who can query those DNS servers, but like Jon mentioned, Google's DNS servers would work as well.
