Forum Discussion

Kannan_Thalaia1's avatar
Nov 25, 2019

Clarification on GTM Resolver cache

In Our environment, in GTM we configured Wide IP and it is providing DNS resolution to local DNS servers.


As the new requirement, We would like the GTM to leverage its resolver for queries of any record it receives under the “” name space.


  1. GTM receive an iterative query for “”
  2. GTM user it resolver to query the DNS forwarders (recursive query)
  3. GTM provide the record back from its resolver cache.


Is it possible with resolver cache or through any other way? Any idea how to achieve it.

4 Replies

  • Since in the new environment the GTM will be receiving iterative (not recursive) queries for the DNS resource records of the MYTEST.SUBDOMAINABC.COM, this means that the DNS servers that are querying for these records believe that the DNS server that their queries are going to is authoritative for the MYTEST.SUBDOMAINABC.COM domain.


    Thus, certainly using DNS Express so that the GTM itself becomes an authoritative secondary nameserver to whatever backend primary nameserver is authoritative for the domain (and will receive and maintain the zone via standard AXFR/IXFR transfers replication) would be an excellent approach. (Alternatively, the GTM can simply act in inline ["middle man"] mode between the client DNS servers and the backend authoritative DNS nameservers, caching their responses [in configured Transparent Cache] for any such future client DNS queries.)

  • The Global Traffic Manager (a.k.a. GTM) and now referred to as DNS, is one of the cutting-edge modules offered on F5 Networks® BIG-IP® platform. “Global” is the right word for this module because it has the ability to make name resolution load balancing decisions for systems located anywhere in the world, not just the US. You can think of the GTM as an intelligent DNS that is security-minded. In other words its logic can make informed decisions on correlating a hostname to an IP address while keeping security in check.