Are you using iptables on Ariel? You shouldn't need to, just define defaults routes on ariel and miranda, run a routing daemon on ariel... rip/ripII should be all you need. Zebra is dead though the "known to be successor" is quagga, BIRD also is working well. routed is a bit heavy for what you want, gated just stop, don't use it. radvd advertising routing daemon heavy.

If I were in your shoes, BIRD seems right, easily configd to only route to and from a network... of course, you could use iptables... but why. Routing is so damned automagic when setup proper, iptables have to be run everytime there is a change, plus you have to turn on tcp-forwarding in the kernel.

And with the DNS issue, MaraDNS needs to be configured to agree to listen and reply on 10.201.1.254:53, 10.200.1.50:53 and 127.0.0.1:53