You can use the NAP Client Configuration console to specify the Health Registration Authority (HRA) servers that a client computer uses to obtain a health certificate. To do this, you must create a trusted server group, which is an ordered list of one or more HRA servers. If there is more than one HRA server listed in a trusted server group, a client computer attempts to contact each HRA server in the order specified until an available server is found.
You must configure a trusted server group only if you are using the Internet Protocol security (IPsec) enforcement client to enforce health policies. The IPsec enforcement client relies on health certificates and HRA servers to enforce health policies. If you are not using the IPsec enforcement client, you do not need to configure trusted server groups.