Which technique encodes malicious content or data of other programs within DNS queries and replies?

Which technique encodes malicious content or data of other programs within DNS queries and replies?

• A. DNS tunneling
• B. ICMP tunneling
• C. IP Identification Field
• D. TCP Initial Sequence Number

Answer: (A)

DNS tunneling is a covert channel that carries data inside DNS queries and responses. By encoding malicious content or data from other programs into the labels of a DNS query—typically as subdomains under an attacker‑controlled domain—an infected host can exfiltrate information or receive commands while the traffic looks like ordinary DNS traffic. The DNS resolver asks the authoritative server for that domain, the server captures and decodes the hidden data, and may respond with records that convey instructions or results. This approach leverages the ubiquity and trust placed in DNS, often allowing it to slip past firewalls that block other protocols. It’s distinct from techniques that hide data in other protocols or header fields, such as ICMP tunneling, IP identification fields, or TCP sequence numbers, which don’t involve DNS messages.

DNS tunneling is a covert channel that carries data inside DNS queries and responses. By encoding malicious content or data from other programs into the labels of a DNS query—typically as subdomains under an attacker‑controlled domain—an infected host can exfiltrate information or receive commands while the traffic looks like ordinary DNS traffic. The DNS resolver asks the authoritative server for that domain, the server captures and decodes the hidden data, and may respond with records that convey instructions or results. This approach leverages the ubiquity and trust placed in DNS, often allowing it to slip past firewalls that block other protocols. It’s distinct from techniques that hide data in other protocols or header fields, such as ICMP tunneling, IP identification fields, or TCP sequence numbers, which don’t involve DNS messages.