DNS Express for CNAME Record Non-authoritative

Hi Lyndon,

This is basically by design because DNS-Express doesn't do any further recursion for that cname. So, your question is maybe targeting using F5 DNS as LDNS via DNS-Express right?

Basically, when a user does a DNS request on his dial-up for instance he will ask first its LDNS (local ISP DNS server) which does ask for a specific A-record (based on DNS iteration) the corresponding authoritative DNS server for the requested RR. If the authoritative DNS server is a BIG-IP with DNS-Express enabled for that zone, it will answer with the particular A-record.

In case the users DNS A-record request would point at the end to a non-authoritative cname on DNS-Express we will just respond with the cname RR only and the LDNS (local ISP DNS for that dial-up) would do the recursion.

I hope it's clear so far.

Now, there many way's to configure the box doing this.

Answer: Layered Virtual

One which does work is, configure an external listener with a "resolver cache" profile (the BIG-IP in that case does recursion to the root-hits by default or as you define). Then define within the cache the "Forward Zones" and point the zone to a second listener (which is internally available only!) and define for that listener a profile which has DNS-Express enabled on it. Done.

It is very simple. We are just acting with the external listener as the LDNS (local ISP DNS server) in front of the internal DNS-Express listener. Finally, we are able to do the recursion for that stuff ;-).

Cheerio, Andrea