CompTIA Network+ Practice Test

What does reverse DNS lookup aim to accomplish?

1. Translate an FQDN to an IP address

2. Resolve an IP address to an FQDN

3. Check the validity of an IP address

4. Find the location of a DNS server

The correct answer is: Resolve an IP address to an FQDN

Reverse DNS lookup is a process that converts an IP address into a Fully Qualified Domain Name (FQDN). This is the fundamental purpose of reverse DNS, which helps identify the domain name associated with a given IP address. This process is typically accomplished using a special type of DNS record known as a PTR (Pointer) record. When a reverse DNS query is made, the DNS system checks its records to find the corresponding FQDN for the specified IP address. This functionality is essential for various applications, including network troubleshooting, email server validation, and enhancing security by ensuring that the IP address corresponds to a legitimate domain. By being able to resolve an IP address back into a domain name, organizations can verify sources of connections and improve their ability to conduct audits on traffic. Other options, although they may relate to DNS in some capacity, do not accurately depict the role of reverse DNS lookup. For instance, converting an FQDN to an IP address represents the process of forward DNS lookup, and checking the validity of an IP address does not directly involve resolving it to a domain name. Similarly, finding the location of a DNS server pertains to a different aspect of network infrastructure management.