An administrator is attempting to troubleshoot a program that is unable to resolve IP addresses from FQDNs. Which of the following commands is used to check reverse DNS settings?

The `dig` command (Domain Information Groper) is a flexible DNS querying tool available on Linux/Unix systems that can perform both forward and reverse DNS lookups. Using `dig -x <IP address>` queries the PTR record for a given IP, which is essential for troubleshooting reverse DNS (FQDN-to-IP resolution failures).

ifconfig displays and configures network interface parameters such as IP address and MAC address but does not perform DNS queries.

nbtstat is a Windows command used to display NetBIOS over TCP/IP statistics and name tables, not DNS records.

The route command displays or modifies the IP routing table and has no capability to query DNS records.