/mcpnot want to use DNS, you can configure Unified Communications Manager and IM and Presence Service to use IP addresses rather than hostnames to communicate with gateways and endpoint devices. You must configure the server to use static IP addressing to ensure that the server obtains a fixed IP address. Using a static IP address also ensures that Cisco Unified IP Phones can register with the application when you plug the phones into the network. Verify DNS Registration Follow this procedure if you use a DNS in your topology. You must verify that all servers to be added are registered in DNS properly by performing the following actions: Procedure Step 1 Open a command prompt. Step 2 To ping each server by its DNS name, enter ping DNS_name. Step 3 To look up each server by IP address, enter nslookup IP_address. DNS requirements Note the following requirements: • Mixed-mode DNS deployments not supported—Cisco does not support mixed-mode deployments. Both Unified Communications Manager and IM and Presence Service must either use or not use DNS. • If your deployment uses DNS—Unified Communications Manager and IM and Presence Service should use the same DNS server. If you use different DNS servers between IM and Presence Service and Unified Communications Manager, it is likely to cause abnormal system behavior. • If your deployment does not use DNS, you will need to edit the following Host Name/IP Address fields: • Server—In the Cisco Unified CM Administration Server Configuration window, set IP addresses for your cluster nodes. • IM and Presence UC Service—In the Cisco Unified CM Administration UC Service Configuration window, create an IM and Presence UC service that points to the IP address of the IM and Presence database publisher node. • CCMCIP Profiles—In the Cisco Unified CM IM and Presence Administration CCMCIP Profile Configuration window, point any CCMCIP profiles to the IP address of the host. • Multinode considerations—If you are using the multinode feature in IM and Presence Service, see the section regarding multinode deployments in the Configuration and Administration of the IM and Presence Service Guide for DNS configuration options. • Ensure that the DNS server is configured on Windows 2019 or above or use the DNS server configured in any Linux Machine. Installation Guide for Cisco Unified Communications Manager and the IM and Presence Service, Release 15 and SUs 18 Planning the Installation Verify DNS Registration