nsupdate reads input records, one per line. Each line contributes a resource record to an update request. All domain names used in a single update request must belong to the same DNS zone. Updates are sent ot the master server as defined in the SOA MNAME field.
A blank line causes the accumulated records to be formatted into a single update request and transmitted to the zone's authoritative name servers. Additional records may follow, which are formed into additional, but completely independent, update requests. End the input with a blank line in order to transmit
the last request.
Records take one of two general forms. Prerequisite records specify conditions that must be satisfied before the request will be processed. Update records specify changes to be made to the DNS database. An update request consists of zero or more prerequisites and one or more updates. Each update
request is processed atomically. All prerequisites must be satisfied, then all updates will be performed.
nsupdate understands the following input record formats:
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prereq nxdomain domain-name
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This format requires that no RR of any type exist with name domain-name.
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prereq yxdomain domain-name
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This format requires that at least one RR names domain-name must exist.
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prereq nxrrset domain-name [class] type
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This format requires that no RR exist of the specified type and domain-name.
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prereq yxrrset domain-name [class] type [data ...]
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This format requires that an RR exist of the specified type and domain-name. If data is specified, it must match exactly.
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update delete domain-name [class] [type [data ...]]
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This format deletes RR's names domain-name. If type (and possibly data) are specified, only matching records will be deleted.
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update add domain-name ttl [class] type data ...
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This format adds a new RR of specified ttl, type and data.
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