Which of the following best explains a zone in DNS?

Which of the following best explains a zone in DNS?

• A. It is the portion of the DNS namespace for which a server is responsible.
• B. It is a security boundary for DNS queries.
• C. It is the time-to-live setting for a domain's records.
• D. It is the list of all domain names registered by a registrar.

Answer: (A)

A DNS zone is the portion of the DNS namespace for which a DNS server is authoritative. In practical terms, a zone defines the set of domain names that a particular server is responsible for answering queries about, and it stores the resource records that describe how to reach those names. The boundary of a zone is established through delegation: higher-level DNS servers point to the zone’s authoritative servers using NS records, and each zone has its own SOA (Start of Authority) and a zone file that can be replicated to secondary servers via zone transfers. This concept best explains the idea because it focuses on who administers and answers for a subset of names in the DNS hierarchy, which is precisely what a zone structure represents. It’s not primarily about security boundaries, per-record TTL values, or a registrar’s registry of registrations, which are distinct concepts in DNS and domain management.

A DNS zone is the portion of the DNS namespace for which a DNS server is authoritative. In practical terms, a zone defines the set of domain names that a particular server is responsible for answering queries about, and it stores the resource records that describe how to reach those names. The boundary of a zone is established through delegation: higher-level DNS servers point to the zone’s authoritative servers using NS records, and each zone has its own SOA (Start of Authority) and a zone file that can be replicated to secondary servers via zone transfers.

This concept best explains the idea because it focuses on who administers and answers for a subset of names in the DNS hierarchy, which is precisely what a zone structure represents. It’s not primarily about security boundaries, per-record TTL values, or a registrar’s registry of registrations, which are distinct concepts in DNS and domain management.