F5 is upgrading its customer support chat feature on My.F5.com. Chat support will be unavailable from 6am-10am PST on 1/20/26. Refer to K000159584 for details.

Forum Discussion

Richard_75751's avatar
Richard_75751
Icon for Nimbostratus rankNimbostratus
Jun 23, 2014

dns express - gtm as secondary dns server

Hi Guys,   I would like to configure gtm to use dns express and act as secondary dns server. The primary dns server is running microsoft intergrated DNS. dns express will be used to transfer any f...
Kevin_Davies_40's avatar
Kevin_Davies_40
Icon for Nacreous rankNacreous
Jun 23, 2014

I think you may have Wide-IP confused with DNS express. Wide-IP is intelligent resolution for FQDN hosts to resources monitored by it. Be it LTM's or any other device. If it cannot find a matching Wide-IP name then it falls back to other DNS resolution methods such as DNS express.

 

DNS Express acts a nameserver on behalf of your existing nameservers. It will become a secondary for the domains so it will take a copy of the entire zone file for any domain it is handling.

 

I am not sure what you gain from forwarding the requests to the internal Microsoft server. You are better off using DNS express for those domains as well. A lot of companies do it this way to protect their internal name servers and utilise the high performance and speed of GTM.

 

Kevin_Davies_40's avatar
Kevin_Davies_40
Icon for Nacreous rankNacreous
Jun 23, 2014
Yes it will. As long as you have told DNS express to secondary those domains then it will answer for them. Don't get wide-ip mixed up with DNS express. Wide-IP configuration will always take precedence and it is configured in GTM, not in your DNS. How it works is simple. GTM will see if a FQDN matches an incoming request in Wide-IP. If not then it will check if the domain has been hosted in DNS express. If not then it will continues to check about five other name resolution configurations it can support to resolve the address. So essentially it falls through to each one if the previous does not provide resolution. The top of that list is Wide-IP.