Saving RAM is more important than saving a few cycles
used by re-creating the request buffer in the error case.
Also reduce the size of the buffer to 128 bytes.
If we are just requesting the AAAA record it is unlikely
for the reply to take up the maximum size of 512 bytes.
We were already placing restrictions on the domain name length,
those are now actually a bit more relaxed (112 bytes instead of 64)
