A user is configuring a new wireless router. Which of the following should be done to ensure that unauthorized changes cannot be made?

Changing the SSID (Service Set Identifier) makes the network name unique or hidden, but it does not prevent someone with physical or network access from attempting to log into the router's management interface using default credentials.

Changing the router's internal IP address (e.g., from 192.168.1.1) makes it slightly harder for attackers to locate the management interface, but it does not prevent access if the default administrator password is known.

Changing the default administrator password on a new wireless router is crucial because default credentials are widely known or easily guessable, posing a significant security risk. A strong, unique administrator password prevents unauthorized individuals from logging into the router's configuration interface and making malicious changes to its settings.

Changing the encryption key (or passphrase) for the wireless network itself secures wireless client communication, but it does not protect the router's administrative interface from unauthorized access if the default login is still active.