Forum Discussion
Livius
Cirrus
CirrusRESOLV::lookup questions
Hi everyone,
I'm using an irule where I use RESOLV::lookup to determine the destination for ongoing connections. I have some concerns about a failure scenario where the FQDN could not be resolved :
- What will happen if we will get a NXDOIMAIN response ?
- In case the DNS server returns multiple A queries, will they all be stored in the cache?
- Is there iRule command that can be used to loop through the returned A queries?
- Will DNS cache TTL over rule the TTL in the response?
Thanks in advance for your answers! Liviu
2 Replies
JGCumulonimbus
Put lookup result in a list: set addr_list [RESOLV::lookup @8.8.8.8 -a example.com" Check if there is any entry found: if { [llength $addr_list] > 0 } { foreach addr_found $addr_list { Do something. } } else { No entry found. }See https://devcentral.f5.com/wiki/irules.resolv__lookup.ashx, which also answers your questions about result caching.
Lee_SutcliffeNacreous
I wrote the following code share that may be useful as it includes a caching feature using subtables.
