dnssec-signzone — DNSSEC zone signing tool


dnssec-signzone [-a] [-c class] [-d directory] [-e end-time] [-f output-file] [-g] [-h] [-k key] [-l domain] [-i interval] [-I input-format] [-j jitter] [-N soa-serial-format] [-o origin] [-O output-format] [-p] [-P] [-r randomdev] [-s start-time] [-t] [-v level] [-z] [-3 salt] [-H iterations] [-A] {zonefile} [key...]


dnssec-signzone signs a zone. It generates NSEC and RRSIG records and produces a signed version of the zone. It also generates a keyset- file containing the key-signing keys for the zone, and if signing a zone which contains delegations, it can optionally generate DS records for the child zones from their keyset- files.



Verify all generated signatures.

-c class

Specifies the DNS class of the zone.

-k key

Treat specified key as a key signing key ignoring any key flags. This option may be specified multiple times.

-l domain

Generate a DLV set in addition to the key (DNSKEY) and DS sets. The domain is appended to the name of the records.

-d directory

Look for keyset files in directory as the directory


If the zone contains any delegations, and there are keyset- files for any of the child zones, then DS records for the child zones will be generated from the keys in those files. Existing DS records will be removed.

-s start-time

Specify the date and time when the generated RRSIG records become valid. This can be either an absolute or relative time. An absolute start time is indicated by a number in YYYYMMDDHHMMSS notation; 20000530144500 denotes 14:45:00 UTC on May 30th, 2000. A relative start time is indicated by +N, which is N seconds from the current time. If no start-time is specified, the current time minus 1 hour (to allow for clock skew) is used.

-e end-time

Specify the date and time when the generated RRSIG records expire. As with start-time, an absolute time is indicated in YYYYMMDDHHMMSS notation. A time relative to the start time is indicated with +N, which is N seconds from the start time. A time relative to the current time is indicated with now+N. If no end-time is specified, 30 days from the start time is used as a default.

-f output-file

The name of the output file containing the signed zone. The default is to append .signed to the input filename.


Prints a short summary of the options and arguments to dnssec-signzone.

-i interval

When a previously-signed zone is passed as input, records may be resigned. The interval option specifies the cycle interval as an offset from the current time (in seconds). If a RRSIG record expires after the cycle interval, it is retained. Otherwise, it is considered to be expiring soon, and it will be replaced.

The default cycle interval is one quarter of the difference between the signature end and start times. So if neither end-time or start-time are specified, dnssec-signzone generates signatures that are valid for 30 days, with a cycle interval of 7.5 days. Therefore, if any existing RRSIG records are due to expire in less than 7.5 days, they would be replaced.

-I input-format

The format of the input zone file. Possible formats are "text" (default) and "raw". This option is primarily intended to be used for dynamic signed zones so that the dumped zone file in a non-text format containing updates can be signed directly. The use of this option does not make much sense for non-dynamic zones.

-j jitter

When signing a zone with a fixed signature lifetime, all RRSIG records issued at the time of signing expires simultaneously. If the zone is incrementally signed, i.e. a previously-signed zone is passed as input to the signer, all expired signatures have to be regenerated at about the same time. The jitter option specifies a jitter window that will be used to randomize the signature expire time, thus spreading incremental signature regeneration over time.

Signature lifetime jitter also to some extent benefits validators and servers by spreading out cache expiration, i.e. if large numbers of RRSIGs don't expire at the same time from all caches there will be less congestion than if all validators need to refetch at mostly the same time.

-n ncpus

Specifies the number of threads to use. By default, one thread is started for each detected CPU.

-N soa-serial-format

The SOA serial number format of the signed zone. Possible formats are "keep" (default), "increment" and "unixtime".


Do not modify the SOA serial number.


Increment the SOA serial number using RFC 1982 arithmetics.


Set the SOA serial number to the number of seconds since epoch.

-o origin

The zone origin. If not specified, the name of the zone file is assumed to be the origin.

-O output-format

The format of the output file containing the signed zone. Possible formats are "text" (default) and "raw".


Use pseudo-random data when signing the zone. This is faster, but less secure, than using real random data. This option may be useful when signing large zones or when the entropy source is limited.


Disable post sign verification tests.

The post sign verification test ensures that for each algorithm in use there is at least one non revoked self signed KSK key, that all revoked KSK keys are self signed, and that all records in the zone are signed by the algorithm. This option skips these tests.

-r randomdev

Specifies the source of randomness. If the operating system does not provide a /dev/random or equivalent device, the default source of randomness is keyboard input. randomdev specifies the name of a character device or file containing random data to be used instead of the default. The special value keyboard indicates that keyboard input should be used.


Print statistics at completion.

-v level

Sets the debugging level.


Ignore KSK flag on key when determining what to sign.

-3 salt

Generate a NSEC3 chain with the given hex encoded salt. A dash (salt) can be used to indicate that no salt is to be used when generating the NSEC3 chain.

-H iterations

When generating a NSEC3 chain use this many interations. The default is 100.


When generating a NSEC3 chain set the OPTOUT flag on all NSEC3 records and do not generate NSEC3 records for insecure delegations.


The file containing the zone to be signed.


Specify which keys should be used to sign the zone. If no keys are specified, then the zone will be examined for DNSKEY records at the zone apex. If these are found and there are matching private keys, in the current directory, then these will be used for signing.


The following command signs the zone with the DSA key generated by dnssec-keygen ( The zone's keys must be in the master file ( This invocation looks for keyset files, in the current directory, so that DS records can be generated from them (-g).

% dnssec-signzone -g -o \

In the above example, dnssec-signzone creates the file This file should be referenced in a zone statement in a named.conf file.

This example re-signs a previously signed zone with default parameters. The private keys are assumed to be in the current directory.

% cp
% dnssec-signzone -o


dnssec-signzone was designed so that it could sign a zone partially, using only a subset of the DNSSEC keys needed to produce a fully-signed zone. This permits a zone administrator, for example, to sign a zone with one key on one machine, move the resulting partially-signed zone to a second machine, and sign it again with a second key.

An unfortunate side-effect of this flexibility is that dnssec-signzone does not check to make sure it's signing a zone with any valid keys at all. An attempt to sign a zone without any keys will appear to succeed, producing a "signed" zone with no signatures. There is no warning issued when a zone is not fully signed.

This will be corrected in a future release. In the meantime, ISC recommends examining the output of dnssec-signzone to confirm that the zone is properly signed by all keys before using it.


dnssec-keygen(8), BIND 9 Administrator Reference Manual, RFC 4033.


Internet Systems Consortium