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41 lines
2.3 KiB
Markdown
41 lines
2.3 KiB
Markdown
---
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name: NO_PURGE
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---
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NO_PURGE indicates that records should not be deleted from a domain.
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Records will be added and updated, but not removed.
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NO_PURGE is generally used in very specific situations:
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* A domain is managed by some other system and DNSControl is only used to insert a few specific records and/or keep them updated. For example a DNS Zone that is managed by ActiveDirectory, but DNSControl is used to update a few, specific, DNS records. In this case we want to specify the DNS records we are concerned with but not delete all the other records. This is a risky use of NO_PURGE since, if NO_PURGE was removed (or buggy) there is a chance you could delete all the other records in the zone, which could be a disaster. That said, domains with some records updated using Dynamic DNS have no other choice.
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* To work-around a pseudo record type that is not supported by DNSControl. For example some providers have a fake DNS record type called "URL" which creates a redirect. DNSControl normally deletes these records because it doesn't understand them. NO_PURGE will leave those records alone.
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In this example DNSControl will insert "foo.example.com" into the
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zone, but otherwise leave the zone alone. Changes to "foo"'s IP
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address will update the record. Removing the A("foo", ...) record
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from dnscontrol will leave the record in place.
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{% include startExample.html %}
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{% highlight js %}
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D("example.com", .... , NO_PURGE,
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A("foo","1.2.3.4")
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);
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{%endhighlight%}
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{% include endExample.html %}
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The main caveat of NO_PURGE is that intentionally deleting records
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becomes more difficult. Suppose a NO_PURGE zone has an record such
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as A("ken", "1.2.3.4"). Removing the record from dnsconfig.js will
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not delete "ken" from the domain. DNSControl has no way of knowing
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the record was deleted from the file The DNS record must be removed
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manually. Users of NO_PURGE are prone to finding themselves with
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an accumulation of orphaned DNS records. That's easy to fix for a
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small zone but can be a big mess for large zones.
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Not all providers support NO_PURGE. For example the BIND provider
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rewrites zone files from scratch each time, which precludes supporting
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NO_PURGE. DNSControl will exit with an error if NO_PURGE is used
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on a driver that does not support it.
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There is also `PURGE` command for completeness. `PURGE` is the
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default, thus this command is a no-op.
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