COMPUTER NETWORKING

Detailed explanation-1: -Port 53 is used for both TCP and UDP communication. For example, when a user types a URL into their web browser, the browser first sends a DNS query to a DNS server to translate the domain name into an IP address. The response from the server is sent back to the browser on the same port-port 53.

Detailed explanation-2: -A DNS client uses a random port above 1023 for both UDP and TCP. You can thus differentiate between the following: A client-to-server query-source port is above 1023, destination port is 53. A server-to-client response-source port is 53, destination port is above 1023.

Detailed explanation-3: -Vulnerabilities in DNS Bypass Firewall Rules (UDP 53) is a Low risk vulnerability that is one of the most frequently found on networks around the world. This issue has been around since at least 1990 but has proven either difficult to detect, difficult to resolve or prone to being overlooked entirely.