When testing F5 DNS failover between two data center sites, it is important to understand the concepts and configurations involved.
DNS > GSLB > Data Centers
1. Data Center Disablement: F5 BIG-IP GTM (Global Traffic Manager) or DNS (in newer versions) can be configured to provide intelligent traffic management across multiple data centers. If you want to simulate a complete data center failure, you can disable the entire data center in the F5 configuration. When a data center is disabled, F5 will stop sending traffic to all the resources (like servers or pools) associated with that data center. This is helpful for testing the scenarios where an entire data center goes offline.
DNS > GSLB > Pools
2. Pool Member Disablement: Pools in F5 are groups of devices (like servers) that are used to serve particular network traffic. A pool member is an individual device within a pool. You can disable specific pool members to test the failover scenario for a separate server (or a few servers). This would simulate the scenario of individual server failures within a data center rather than the entire data center going offline.
In summary, disabling a Data Center is a broad approach that simulates the entire data center going down, and disabling a Pool Member is more granular, simulating the failure of a specific server or resource. Both approaches can be used depending on the scenario you aim to test.
Please also note that when performing such tests, it’s important to ensure proper communication with stakeholders and monitoring of the systems to avoid any unintended impacts on services or applications.