[dns-operations] good async DNS library

[Klaus Darilion]

Hi all!

For various monitoring scripts we use Perl's NET::DNS and 
Net::DNS::Async. Unfortunately they have various problems, ie 
Net::DNS::Async does not support DNSSEC and sending to other ports than 
54, with Net::DNS's timeout/retries settings I never get the expected 
results ....

Can someon recommend a DNS library (Perl, Python or PHP preferred) that 
supports:
- async resolving
- setting DO bit
- EDNS0 options
- proper timeout handling
- sending queries to non-standard ports
- (optional: TCP fallback)

Thanks
Klaus