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.
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, www.store.siterequest.com and www.checkout.siterequest.com. These wide IPs correspond to the two web applications.
A listener is a specialized virtual server that uses port 53 and to which you assign a specific IP address. When traffic is sent to that IP address, the listener alerts BIG-IP GTM and the system either handles the traffic locally or forwards the traffic to the appropriate resource.
You control how BIG-IP GTM responds to network traffic on a per-listener basis. The number of listeners you create depends on your network configuration and the destinations to which you want to send specific DNS requests. For example, a single BIG-IP GTM can be the primary authoritative server for one domain, while forwarding other DNS requests to a different DNS server. Regardless of how many listeners you configure, BIG-IP GTM always manages and responds to requests for the wide IPs that you have configured on the system.
Perform these tasks to delegate DNS traffic to wide IPs.
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.