Managing Records¶
While zones are used to break up the DNS namespace into a hierarchy, ‘resource records’, or simply ‘records’, are used to store data within the namespace. Each record has a
Name: the string that indicates its location in the DNS namespace.
Type: the set of letter codes that identify the record’s usage. For example
Afor an address record orCNAMEfor a canonical name record.Class: the set of letter codes that specify the namespace for the record. Typically, this is
INfor internet, though other namespaces do exist.TTL: the duration in seconds that the record remains valid.
Rdata: the data for the record, such as an IP address for an
Atype record or another record name for aCNAMEtype record.
Recordsets in Designate¶
DNS records in Designate are managed using Recordsets, which represent one
or more DNS records with the same Name and Type, but potentially different
data. For example, a recordset named www.example.com, with a type of A,
that contains the data 192.0.2.1 and 192.0.2.2 might reflect two web
servers hosting www.example.com located at those two IP addresses.
You must create Recordsets within a zone. If you delete a zone that contains recordsets, those recordsets within the zone are also deleted.
Creating a recordset¶
By default, any user can create Recordsets in zones that their project owns.
In this example, a user has created a zone named example.org..
Recordsets are created using the openstack recordset create command and
require a zone, a name, a type, and data for the record.
To recreate the earlier example using the OpenStack client with the Designate
plugin, the user would run:
$ openstack recordset create --type A --record 192.0.2.1 example.org. www +-------------+--------------------------------------+ | Field | Value | +-------------+--------------------------------------+ | action | CREATE | | created_at | 2021-05-03T03:13:46.000000 | | description | None | | id | 549c3e83-443f-474b-b467-6bcd7cb9f37d | | name | www.example.org. | | project_id | c85fdba96041438fa0cad2dc7909d3f5 | | records | 192.0.2.1 | | status | PENDING | | ttl | None | | type | A | | updated_at | None | | version | 1 | | zone_id | 077460ef-34db-486a-8d59-c9564dc3a3a9 | | zone_name | example.org. | +-------------+--------------------------------------+
As the final argument www is not a fully qualified domain name (FQDN) it
is prepended to the zone name. You can achieve the same result using the FQDN,
www.example.org.. Note that the trailing . is required when using the
FQDN. Omitting it results in the name, "www.example.org.example.org.".
You can supply the --record argument multiple times to create multiple
records within the recordset. A typical use for this is Round-robin DNS.
$ openstack recordset create --type A --record 192.0.2.1 --record 192.0.2.2 example.org. web +-------------+--------------------------------------+ | Field | Value | +-------------+--------------------------------------+ | action | CREATE | | created_at | 2021-05-03T03:26:43.000000 | | description | None | | id | 9e0fba43-ca67-44ed-b9d9-fc1242920319 | | name | web.example.org. | | project_id | c85fdba96041438fa0cad2dc7909d3f5 | | records | 192.0.2.1 | | | 192.0.2.2 | | status | PENDING | | ttl | None | | type | A | | updated_at | None | | version | 1 | | zone_id | 077460ef-34db-486a-8d59-c9564dc3a3a9 | | zone_name | example.org. | +-------------+--------------------------------------+
You can view the recordsets for a zone using the openstack recordset list
command:
$ openstack recordset list example.org. +--------------------------------------+------------------+------+---------------------------------------------------------------------+--------+--------+ | id | name | type | records | status | action | +--------------------------------------+------------------+------+---------------------------------------------------------------------+--------+--------+ | 3bebbd03-07d7-4274-a784-39c32a2be8c6 | example.org. | SOA | ns1.example.net. admin.example.org. 1620012616 3599 600 86400 3600 | ACTIVE | NONE | | 7d34e4d3-a2f1-4af0-831c-ba52a8312c6a | example.org. | NS | ns1.example.net. | ACTIVE | NONE | | 9e0fba43-ca67-44ed-b9d9-fc1242920319 | web.example.org. | A | 192.0.2.1 | ACTIVE | NONE | | | | | 192.0.2.2 | | | | 549c3e83-443f-474b-b467-6bcd7cb9f37d | www.example.org. | A | 192.0.2.1 | ACTIVE | NONE | +--------------------------------------+------------------+------+---------------------------------------------------------------------+--------+--------+
The SOA and NS records for the zone are also visible here, but cannot
be modified.
The authoritative nameserver for the zone is listed as the record data for the
NS type record of the zone, which in this example is ns1.example.net..
To verify this you can query the nameserver using dig for the NS type:
$ dig @ns1.example.net example.org. -t NS +short ns1.devstack.org.
You can also verify the A recordsets. You don’t need the -t option
because it is the default:
$ dig @ns1.example.net web.example.org. +short 192.0.2.2 192.0.2.1 $ dig @ns1.example.net www.example.org. +short 192.0.2.1
If you want to construct a TXT record that exceeds the 255-octet
maximum length of a character-string, it has to be split into
multiple strings as defined in RFC7208 section 3.3. For example,
"v=DKIM1; .... firstsecond string..." can become
"v=DKIM1; .... first" "second string...". If you provide a record
data with less than 255 characters, it will be treated as a
single character-string and validated for empty spaces outside quotes
and unescaped double quotation marks as in RFC1035 section 5.1.
For example, to create a TXT record made of one string of 410
characters you can split it into 2 to like this:
$ openstack recordset create --type TXT --record '"210 characters string" "200 characters string"' example.org. _domainkey
Updating a recordset¶
You can modify a recordset by using the openstack recordset set command.
When updating a recordset by name, you must use the FQDN. As with most
OpenStack commands, you can also use recordset ID. For example, to update
the recordset www.example.org. to contain two records, you could use
the following:
$ openstack recordset set example.org. www.example.org. --record 192.0.2.1 --record 192.0.2.2 +-------------+--------------------------------------+ | Field | Value | +-------------+--------------------------------------+ | action | UPDATE | | created_at | 2021-05-03T03:30:16.000000 | | description | None | | id | 549c3e83-443f-474b-b467-6bcd7cb9f37d | | name | www.example.org. | | project_id | c85fdba96041438fa0cad2dc7909d3f5 | | records | 192.0.2.2 | | | 192.0.2.1 | | status | PENDING | | ttl | None | | type | A | | updated_at | 2021-05-03T03:44:16.000000 | | version | 5 | | zone_id | 077460ef-34db-486a-8d59-c9564dc3a3a9 | | zone_name | example.org. | +-------------+--------------------------------------+
Deleting a recordset¶
You can use the openstack recordset delete command to remove recordsets
using the zone and either the FQDN or the recordset ID.
$ openstack recordset delete example.org. web.example.org. +-------------+--------------------------------------+ | Field | Value | +-------------+--------------------------------------+ | action | DELETE | | created_at | 2021-05-03T03:47:00.000000 | | description | None | | id | 5ab3418f-5377-47eb-b967-9e9ff7f3c26b | | name | web.example.org. | | project_id | c85fdba96041438fa0cad2dc7909d3f5 | | records | 192.0.2.1 | | | 192.0.2.2 | | status | PENDING | | ttl | None | | type | A | | updated_at | 2021-05-03T03:47:13.000000 | | version | 2 | | zone_id | 077460ef-34db-486a-8d59-c9564dc3a3a9 | | zone_name | example.org. | +-------------+--------------------------------------+
