Not sure if this goes here or on serverfault, but here it goes. I have an account with Fastmail where I host my email. So my domain (simulplex.net) currently resolves to that, including WWW as well (they have that option). The domain is registered with godaddy, and the name servers there are the Fastmail ones.
Now, I want to host www.simulplex.net on Arvixe but I've never done separate DNS resolution (if that's the term); I'd like to host a website with them but keep my email with FastMail. I was wondering if that's more easily accomplished through godaddy, or assuming a standard DNS configuration screen, how would I forward A record queries to Arxive and MX queries to Fastmail.