BIG-IP® Global Traffic Manager™ (GTM™) resolves DNS queries that match a wide IP name. BIG-IP GTM can work in conjunction with an existing DNS server on your network. In this situation, you configure the DNS server to delegate wide IP-related requests to BIG-IP GTM for name resolution.
Traffic flow when DNS server delegates traffic to BIG-IP GTM
This implementation focuses on the fictional company SiteRequest that recently purchased BIG-IP GTM to help resolve queries for two web-based applications: store.siterequest.com and checkout.siterequest.com. These applications are delegated zones of www.siterequest.com. Currently, a DNS server manages www.siterequest.com.
SiteRequest administrators have already configured BIG-IP GTM with two wide IPs, store.wip.siterequest.com and checkout.wip.siterequest.com. These wide IPs correspond to the two web applications.
A listener is a specialized virtual server that passively checks for DNS packets on port 53 and the IP address you assign to the listener. When a DNS query is sent to the IP address of the listener, BIG-IP GTM™ either handles the request locally or forwards the request to the appropriate resource.
Perform these tasks to delegate DNS traffic to wide IPs on BIG-IP GTM™.
Determine which DNS servers will delegate wide IP-related requests to BIG-IP® GTM™.
If you are using BIND servers and you are unfamiliar with how to modify the files on these servers, consider reviewing the fifth edition of DNS and BIND, available from O’Reilly Media.
You now have an implementation of BIG-IP® GTM™ in which the DNS server manages DNS traffic unless the query is for store.sitrequest.com or checkout.siterequest.com. When the DNS server receives these queries, it delegates them to BIG-IP GTM, which then load balances the queries to the appropriate wide IPs.