BIG-IP® DNS performs intelligent probing of your network resources to determine whether the resources are up or down. In some circumstances, for example, if your network contains firewalls, you might want to set up device-specific probing to specify which BIG-IP® systems probe specific servers for health and performance data.
A Prober pool is an ordered collection of one or more BIG-IP® systems. BIG-IP DNS can be a member of more than one Prober pool, and a Prober pool can be assigned to an individual server or a data center. When you assign a Prober pool to a data center, by default, the servers in that data center inherit that Prober pool.
The members of a Prober pool perform monitor probes of servers to gather data about the health and performance of the resources on the servers. BIG-IP DNS makes load balancing decisions based on the gathered data. If all of the members of a Prober pool are marked down, or if a server has no Prober pool assigned, BIG-IP DNS reverts to a default intelligent probing algorithm to gather data about the resources on the server.
This figure illustrates how Prober pools work. BIG-IP DNS contains two BIG-IP Local Traffic Manager™ (LTM™) systems that are assigned Prober pools and one BIG-IP LTM system that is not assigned a Prober pool:
BIG-IP systems with prober pools
The status of a Prober pool also indicates the status of the members of the pool. If at least one member of a Prober pool has green status (Available), the Prober pool has green status.
The status of a Prober pool member indicates whether the BIG-IP DNS system, on which you are viewing status, can establish an iQuery connection with the member.
You can view the number of successful and failed probe requests that the BIG-IP® DNS system (on which you are viewing statistics) made to the Prober pools. These statistics reflect only the number of Probe requests and their success or failure. These statistics do not reflect the actual probes that the pool members made to servers on your network.
Prober pool statistics are not aggregated among the BIG-IP DNS systems in a synchronization group. The statistics on one BIG-IP DNS include only the requests made from that BIG-IP DNS system.
Perform these tasks to configure device-specific probing and statistics collection.
|Disabled||The system does not use the discovery feature to automatically add virtual servers. This is the default value. Use this option for a standalone BIG-IP DNS system or for a BIG-IP DNS/LTM® combo system when you plan to manually add virtual servers to the system, or if your network uses multiple route domains.|
|Enabled||The system uses the discovery feature to automatically add virtual servers. Use this option for a BIG-IP DNS/LTM combo system when you want the BIG-IP DNS system to discover LTM virtual servers.|
|Enabled (No Delete)||The system uses the discovery feature to automatically add virtual servers and does not delete any virtual servers that already exist. Use this option for a BIG-IP DNS/LTM combo system when you want the BIG-IP DNS system to discover LTM virtual servers.|
|Round Robin||BIG-IP DNS load balances monitor probes among the members of a Prober pool in a circular and sequential pattern.|
|Global Availability||BIG-IP DNS selects the first available Prober pool member to perform a monitor probe.|
|Inherit from Data Center||By default, a server inherits the Prober pool assigned to the data center in which the server resides.|
|Prober pool name||Select the Prober pool that contains the BIG-IP systems that you want to perform monitor probes of this server.|
You now have an implementation in which a specific BIG-IP® system probes the resources on a specific server, or the servers in a specific data center.