CCNA Practice Exam 2025 – Complete Study Resource

The command to add the IP address of a DNS server in Cisco configuration mode is "ip name-server." This command is used within the global configuration mode to specify the DNS server's IP address that the device will use for name resolution.

When you enter "ip name-server" followed by the IP address, the router or switch can effectively resolve domain names to IP addresses by querying the specified DNS server. This is essential for operations where devices need to look up hostnames rather than working solely with IP addresses.

The other options presented do not correspond to valid Cisco commands for configuring DNS settings. For example, "set dns-server," "configure dns," and "dns server add" are not recognized syntax in Cisco IOS, so they wouldn't yield the desired result of adding a DNS server for name resolution in the device’s configuration. Understanding the correct command allows network professionals to ensure proper DNS configuration as part of network management and troubleshooting.