Ok I found it.
Usage Guidelines The first name server that is added with the ip name-server command occupies the first position and the system uses that server first to resolve the IP addresses. You can add name servers to the system using IPv4 or IPv6 addresses. You can configure one to three IPv4 addresses through a single command. If you have already configured the system with four name servers, you must remove at least one server to add additional name servers. To place a name server in the first position so that the subsystem uses it first, you must remove all name servers with the no form of this command before you proceed. You can choose not to restart the Cisco ISE server; nevertheless, the changes will take effect. If you have the PAN auto-failover configuration enabled in your deployment, the following message appears: PAN Auto Failover is enabled, this operation is not allowed! Please disable PAN Auto-failover first.
Example 1 ise/admin(config)# ip name-server ? Primary DNS server IP address DNS server 2 IP address DNS server 3 IP address IPv6 DNS server address ise/admin(config)# ip name-server
Example 2 You can see the following output after you configure the IP name server. ise/admin# show run | in name-server ip name-server 171.70.168.183 171.68.226.120 64.102.6.247 ip name-server 3201:db8:0:20:f41d:eee:7e66:4eba ise/admin#
Example 3 ise/admin(config)# ip name-server ? ip name-server 10.126.107.120 10.126.107.107 10.106.230.244 DNS Server was modified. If you modified this setting for AD connectivity, you must restart ISE for the change to take effect. Do you want to restart ISE now? (yes/no)
