Unstuck looking at DNS monitoring

Hi,

 

 

I'm looking at putting in a DNS pool / virtual to reerence in a RESOLV::lookup call in an iRule but I'm unsure what the best way to monitor it is.

 

 

On one hand there's the UDP send / recieve approach, which I wanted to use as there are no external scripts etc., but as I don't care / know what the correct repsonse is for a given name, I can't hard code the IP in hex into the recv string. And without the IP, the pattern matching you're left with is very flimsy.... look for an A / IN answer, a gap for a TTL and then an RLENGTH of 4... 00010001.*0004.* it's not very robust is it?? Is it possible to match any single hex character (well... a byte I guess it technically is) in the repsonse? if I could at least fix the exact position of the string, that'd be a big help.

 

 

And so the other hand is an external script, but then again the examples i see on devcentral seem to work by expecting a specific IP in the response. I just need to monitor that a server is evidently chatting DNS happily. If I moniotr google.com from it, I'm clearly never going to be able to know exactly what IP I should get. Maybe I can simply just use host and check the exit code?

 

 

Any thoughts on the best way to do this on V10.2 I'd be really keen to hear.