312-50V9 · Question #532
One of your team members has asked you to analyze the following SOA record. What is the version? Rutgers.edu.SOA NS1.Rutgers.edu ipad.college.edu (200302028 3600 3600 604800 2400.
The correct answer is A. 200303028. The serial number is the first numeric field in a DNS SOA record and serves as the zone's version identifier used by secondary nameservers to detect changes.
Question
One of your team members has asked you to analyze the following SOA record. What is the version? Rutgers.edu.SOA NS1.Rutgers.edu ipad.college.edu (200302028 3600 3600 604800 2400.
Options
- A200303028
- B3600
- C604800
- D2400
- E60
- F4800
How the community answered
(28 responses)- A89% (25)
- B4% (1)
- D4% (1)
- E4% (1)
Why each option
The serial number is the first numeric field in a DNS SOA record and serves as the zone's version identifier used by secondary nameservers to detect changes.
The serial number (200302028 in the record, corresponding to choice A) is the first value in the SOA parenthetical group and acts as the zone file's version number. Secondary nameservers compare their stored serial number against the primary's to determine whether a zone transfer is required. Zone administrators typically format this as YYYYMMDDNN (year, month, day, revision) to make versioning human-readable.
3600 represents either the refresh interval or the retry interval - neither is the version/serial field.
604800 is the expire value, which controls how long secondaries serve data without a successful refresh from the primary.
2400 is the minimum TTL used for negative caching of NXDOMAIN responses, not the version identifier.
The value 60 does not appear anywhere in this SOA record.
The value 4800 does not appear anywhere in this SOA record.
Concept tested: DNS SOA record serial number as zone version
Source: https://www.rfc-editor.org/rfc/rfc1035
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