dnsmasq – Whitelist All Subdomains with Rebind-Domain-OK

There is no wildcard way of doing this - you need to either implement a DNS server, or keep adding entries to your hosts file.

If you do go with installing a DNS server, you don't need to install bind - you can install a simple caching DNS server like totd, dnsmasq, or maradns.

Regardless of what you do, you'll need to make sure that resolv.conf contains the new DNS server, and the following entry must appear in there (in this example, the DNS server is installed on localhost)...

nameserver 127.0.0.1

This is entirely feasible. In bind, the wildcard line would look like this

*.example.com.        IN      A       1.2.3.4