Which DNS record indicates the version of the zone file?

Which DNS record indicates the version of the zone file?

• A. A record
• B. MX record
• C. SOA record version
• D. NS record

Answer: (C)

The Start of Authority (SOA) record contains administrative metadata about a DNS zone, including a serial number that serves as the zone’s version. When you update the zone data, you increment this serial number so secondary DNS servers know that a refresh is needed. That serial is precisely how the zone file’s version is tracked. Other common record types don’t carry a version indicator: A records map names to IPv4 addresses, MX records designate mail exchangers, and NS records list the authoritative name servers for the zone. None of these include a zone-serial field, so they don’t indicate the zone’s version.

The Start of Authority (SOA) record contains administrative metadata about a DNS zone, including a serial number that serves as the zone’s version. When you update the zone data, you increment this serial number so secondary DNS servers know that a refresh is needed. That serial is precisely how the zone file’s version is tracked.

Other common record types don’t carry a version indicator: A records map names to IPv4 addresses, MX records designate mail exchangers, and NS records list the authoritative name servers for the zone. None of these include a zone-serial field, so they don’t indicate the zone’s version.