60 lines
2.1 KiB
Markdown
60 lines
2.1 KiB
Markdown
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## ZONE06: SOA 'minimum' maximum value
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### Test case identifier
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**ZONE06** SOA 'minimum' maximum value
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### Objective
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The SOA minimum field sets the default TTL for all records in a zone.
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The recommended value is to be "cache-friendly". However, for a zone
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that changes content often, there is a need to keep the TTL values
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shorter. The use of the SOA minimum value today is the negative cache
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(where a resolver find content is missing).
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The SOA minimum field is described in section 3.3.13 in
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[RFC 1035](https://datatracker.ietf.org/doc/html/rfc1035), and clarified in
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section 2.2 of [RFC 1912](https://datatracker.ietf.org/doc/html/rfc1912).
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The description of the implementation of negative caching is in
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[RFC 2308](https://datatracker.ietf.org/doc/html/rfc2308) (although it has been
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updated by several DNSSEC related RFCs, it is still relevant for this
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purpose).
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The [RIPE-203](https://www.ripe.net/publications/docs/ripe-203) recommendation
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for the minimum value 2 days, but the negative caching is now the norm.
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DNSCheck has a recommended value of between 300 seconds (5 minutes) and
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86400 seconds (1 day).
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### Inputs
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The domain name to be tested.
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### Ordered description of steps to be taken to execute the test case
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1. Obtain a set of name server IP addresses using [Method4] and [Method5].
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2. Create a SOA query for the zone.
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3. Send the SOA query over UDP to each name server IP address until
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a response is received or until the set is exhausted.
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4. If the answer from step 3 is not authoritative, iterate step 3 until there is an authoritative answer.
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5. Retrieve the SOA minimum value from the SOA record.
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6. If the minimum value is larger than 86400 seconds (1 day), this test
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case fails.
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7. If the minimum value is lower than 300 seconds (5 minutes), this test case
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fails.
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### Outcome(s)
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If the minimum value is larger than 86400 seconds or if the minimum value is
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lower than 300 seconds, this test case fails.
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### Special procedural requirements
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None.
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### Intercase dependencies
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None.
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-------
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[Method4]: ../Methods.md#method-4-obtain-glue-address-records-from-parent
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[Method5]: ../Methods.md#method-5-obtain-the-name-server-address-records-from-child
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