312-50V9 Question #532: Real Exam Question with Answer & Explanation

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

Explanation

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.

Common mistakes.

B. 3600 represents either the refresh interval or the retry interval - neither is the version/serial field.
C. 604800 is the expire value, which controls how long secondaries serve data without a successful refresh from the primary.
D. 2400 is the minimum TTL used for negative caching of NXDOMAIN responses, not the version identifier.
E. The value 60 does not appear anywhere in this SOA record.
F. The value 4800 does not appear anywhere in this SOA record.

Concept tested. DNS SOA record serial number as zone version

Reference. https://www.rfc-editor.org/rfc/rfc1035

Community Discussion

No community discussion yet for this question.

Full 312-50V9 Practice