+ rewrites: support IP exception
host.com -> 1.2.3.4
host.com -> AAAA
Response:
A:
A = 1.2.3.4
AAAA:
AAAA = <IPv6 address of host.com>
+ rewrites: support "pass A only" case
host.com -> A
Response:
A:
A = <IPv4 address of host.com>
AAAA:
<empty>
*.host -> IP
my.host -> my.host
*.my.host -> *.my.host
Requests for my.host and *.my.host will be passed to upstream servers,
while all other requests for *.host will be answered with a rewritten IP