Manage DNS records and recordsets in Azure DNS using the Azure CLI

Artikkeli
11/30/2023

This article shows you how to manage DNS records for your DNS zone by using the cross-platform Azure CLI. Azure CLI is available for Windows, Mac, and Linux. You can also manage your DNS records using Azure PowerShell or the Azure portal.

The examples in this article assume you've already installed the Azure CLI, signed in, and created a DNS zone.

Introduction

Before creating DNS records in Azure DNS, you first need to understand how Azure DNS organizes DNS records into DNS record sets.

Record names

In Azure DNS, records are specified by using relative names. A fully qualified domain name (FQDN) includes the zone name, whereas a relative name doesn't. For example, the relative record name www in the zone contoso.com gives the fully qualified record name www.contoso.com.

An apex record is a DNS record at the root (or apex) of a DNS zone. For example, in the DNS zone contoso.com, an apex record also has the fully qualified name contoso.com (this is sometimes called a naked domain). By convention, the relative name '@' is used to represent apex records.

Record types

Each DNS record has a name and a type. Records are organized into various types according to the data they contain. The most common type is an 'A' record, which maps a name to an IPv4 address. Another common type is an 'MX' record, which maps a name to a mail server.

Azure DNS supports all common DNS record types: A, AAAA, CAA, CNAME, MX, NS, PTR, SOA, SRV, and TXT. Note that SPF records are represented using TXT records.

Additional record types are supported if the zone is signed with DNS Security Extensions (DNSSEC), such as Delegation Signer (DS) and Transport Layer Security Authentication (TLSA) resource records.

DNSSEC resource record types such as DNSKEY, RRSIG, and NSEC3 records are added automatically when a zone is signed with DNSSEC. These types of DNSSEC resource records can't be created or modified after zone signing.

Record sets

Sometimes you need to create more than one DNS record with a given name and type. For example, suppose the 'www.contoso.com' web site is hosted on two different IP addresses. The website requires two different A records, one for each IP address. Here's an example of a record set:

www.contoso.com.        3600    IN    A    134.170.185.46
www.contoso.com.        3600    IN    A    134.170.188.221

Azure DNS manages all DNS records using record sets. A record set (also known as a resource record set) is the collection of DNS records in a zone that have the same name and are of the same type. Most record sets contain a single record. However, examples like the one above, in which a record set contains more than one record, aren't uncommon.

For example, suppose you have already created an A record 'www' in the zone 'contoso.com', pointing to the IP address '134.170.185.46' (the first record above). To create the second record you would add that record to the existing record set, rather than create an additional record set.

The SOA and CNAME record types are exceptions. The DNS standards don't permit multiple records with the same name for these types, therefore these record sets can only contain a single record.

For more information about DNS records in Azure DNS, see DNS zones and records.

Create a DNS record

To create a DNS record, use the az network dns record-set <record-type> add-record command (where <record-type> is the type of record, i.e a, srv, txt, etc.) For help, see az network dns record-set --help.

When creating a record, you need to specify the following information:

Resource group name
Zone name
Record set name
Record type

The record set name given must be a relative name, meaning it must exclude the zone name. If the record set doesn't already exist, this command will create it for you. This command however will add the record you specify if the record set already exist.

If a new record set is created, a default time-to-live (TTL) of 3600 is used. For instructions on how to use different TTLs, see Create a DNS record set.

The following example creates an A record called www in the zone contoso.com in the resource group MyResourceGroup. The IP address of the A record is 203.0.113.11.

az network dns record-set a add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name www --ipv4-address 203.0.113.11

To create a record set in the apex of the zone (in this case, "contoso.com"), use the record name "@", including the quotation marks:

az network dns record-set a add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name "@" --ipv4-address 203.0.113.11

Create a DNS record set

In the above examples, the DNS record was either added to an existing record set, or the record set was created implicitly. You can also create the record set explicitly before adding records to it. Azure DNS supports 'empty' record sets, which can act as a placeholder to reserve a DNS name before creating DNS records. Empty record sets are visible in the Azure DNS control plane, but don't appear on the Azure DNS name servers.

Record sets are created using the az network dns record-set <record-type> create command. For help, see az network dns record-set <record-type> create --help.

Creating the record set explicitly allows you to specify record set properties such as the Time-To-Live (TTL) and metadata. Record set metadata can be used to associate application-specific data with each record set, as key-value pairs.

The following example creates an empty record set of type 'A' with a 60-second TTL, by using the --ttl parameter (short form -l):

az network dns record-set a create --resource-group myresourcegroup --zone-name contoso.com --name www --ttl 60

The following example creates a record set with two metadata entries, "dept=finance" and "environment=production", by using the --metadata parameter:

az network dns record-set a create --resource-group myresourcegroup --zone-name contoso.com --name www --metadata "dept=finance" "environment=production"

Having created an empty record set, records can be added using azure network dns record-set <record-type> add-record as described in Create a DNS record.

Create records of other types

Having seen in detail how to create 'A' records, the following examples show how to create record of other record types supported by Azure DNS.

The parameters used to specify the record data vary depending on the type of the record. For example, for a record of type "A", you specify the IPv4 address with the parameter --ipv4-address <IPv4 address>. The parameters for each record type can be listed using az network dns record-set <record-type> add-record --help.

In each case, we show how to create a single record. The record is added to the existing record set, or a record set created implicitly. For more information on creating record sets and defining record set parameter explicitly, see Create a DNS record set.

There's no example for create an SOA record set, since SOAs are created and deleted with each DNS zone. The SOA record can't be created or deleted separately. However, the SOA can be modified, as shown in a later example.

Create an AAAA record

az network dns record-set aaaa add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name test-aaaa --ipv6-address FD00::1

Create a CAA record

az network dns record-set caa add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name test-caa --flags 0 --tag "issue" --value "ca1.contoso.com"

Create a CNAME record

Note

The DNS standards do not permit CNAME records at the apex of a zone (--Name "@"), nor do they permit record sets containing more than one record.

For more information, see CNAME records.

az network dns record-set cname set-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name test-cname --cname www.contoso.com

Create an MX record

In this example, we use the record set name "@" to create the MX record at the zone apex (in this case, "contoso.com").

az network dns record-set mx add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name "@" --exchange mail.contoso.com --preference 5

Create an NS record

az network dns record-set ns add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name test-ns --nsdname ns1.fabrikam.com

Create a PTR record

In this case, 'my-arpa-zone.com' represents the ARPA zone representing your IP range. Each PTR record set in this zone corresponds to an IP address within this IP range. The record name '10' is the last octet of the IP address within this IP range represented by this record.

az network dns record-set ptr add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name my-arpa.zone.com --ptrdname myservice.contoso.com

Create an SRV record

When creating an SRV record set, specify the _service and _protocol in the record set name. There's no need to include "@" in the record set name when creating an SRV record set at the zone apex.

az network dns record-set srv add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name _sip._tls --priority 10 --weight 5 --port 8080 --target sip.contoso.com

Create a TXT record

The following example shows how to create a TXT record. For more information about the maximum string length supported in TXT records, see TXT records.

az network dns record-set txt add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name test-txt --value "This is a TXT record"

Get a record set

To retrieve an existing record set, use az network dns record-set <record-type> show. For help, see az network dns record-set <record-type> show --help.

When creating a record or record set, the record set name given must be a relative name. This name doesn't include the zone name. You also need to specify the record type, the zone containing the record set, and the resource group containing the zone.

The following example retrieves the record www of type A from zone contoso.com in resource group MyResourceGroup:

az network dns record-set a show --resource-group myresourcegroup --zone-name contoso.com --name www

List record sets

You can list all records in a DNS zone by using the az network dns record-set list command. For help, see az network dns record-set list --help.

This example returns all record sets in the zone contoso.com, in resource group MyResourceGroup:

az network dns record-set list --resource-group myresourcegroup --zone-name contoso.com

This example returns all record sets that match the given record type (in this case, 'A' records):

az network dns record-set a list --resource-group myresourcegroup --zone-name contoso.com

Add a record to an existing record set

You can use az network dns record-set <record-type> add-record both to create a record in a new record set, or to add a record to an existing record set.

For more information, see Create a DNS record and Create records of other types above.

Remove a record from an existing record set.

To remove a DNS record from an existing record set, use az network dns record-set <record-type> remove-record. For help, see az network dns record-set <record-type> remove-record -h.

This command deletes a DNS record from a record set. If the last record in a record set is deleted, the record set itself is also deleted. To keep the empty record set instead, use the --keep-empty-record-set option.

When you use the az network dns record-set <record-type> add-record command, you need to specify the record getting deleted and the zone to delete from. These parameters are described in Create a DNS record and Create records of other types above.

The following example deletes the A record with value '203.0.113.11' from the record set named www in the zone contoso.com, in the resource group MyResourceGroup.

az network dns record-set a remove-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name "www" --ipv4-address 203.0.113.11

Modify an existing record set

Each record set contains a time-to-live (TTL), metadata, and DNS records. The following sections explain how to modify each of these properties.

To modify an A, AAAA, CAA, MX, NS, PTR, SRV, or TXT record

To modify an existing record of type A, AAAA, CAA, MX, NS, PTR, SRV, or TXT, you should first add a new record and then delete the existing record. For detailed instructions on how to delete and add records, see the earlier sections of this article.

The following example shows how to modify an 'A' record, from IP address 203.0.113.11 to IP address 203.0.113.22:

az network dns record-set a add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name www --ipv4-address 203.0.113.22
az network dns record-set a remove-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name www --ipv4-address 203.0.113.11

You can't add, remove, or modify the records in the automatically created NS record set at the zone apex (--Name "@", including quote marks). For this record set, the only changes permitted are to modify the record set TTL and metadata.

To modify a CNAME record

Unlike most other record types, a CNAME record set can only contain a single record. That's why you can't replace the current value by adding a new record and removing the existing record like other record types.

Instead, to modify a CNAME record, use az network dns record-set cname set-record. For help, see az network dns record-set cname set-record --help

The example modifies the CNAME record set www in the zone contoso.com, in resource group MyResourceGroup, to point to 'www.fabrikam.net' instead of its existing value:

az network dns record-set cname set-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name test-cname --cname www.fabrikam.net

To modify an SOA record

Unlike most other record types, a SOA record set can only contain a single record. That's why you can't replace the current value by adding a new record and removing the existing record like other record types.

Instead, to modify the SOA record, use az network dns record-set soa update. For help, see az network dns record-set soa update --help.

The following example shows how to set the 'email' property of the SOA record for the zone contoso.com:

az network dns record-set soa update --resource-group myresourcegroup --zone-name contoso.com --email admin.contoso.com

To modify NS records at the zone apex

The NS record set at the zone apex is automatically created with each DNS zone. It contains the names of the Azure DNS name servers assigned to the zone.

You can add more name servers to this NS record set, to support cohosting domains with more than one DNS provider. You may also modify the TTL and metadata for this record set. However, you can't remove or modify the pre-populated Azure DNS name servers.

This restriction applies only to the NS record set at the zone apex. Other NS record sets in your zone (as used to delegate child zones) can be modified without constraint.

The following example shows how to add another name server to the NS record set at the zone apex:

az network dns record-set ns add-record --resource-group myresourcegroup --zone-name contoso.com --record-set-name "@" --nsdname ns1.fabrikam.com

To modify the TTL of an existing record set

To modify the TTL of an existing record set, use azure network dns record-set <record-type> update. For help, see azure network dns record-set <record-type> update --help.

The following example shows how to modify a record set TTL, in this case to 60 seconds:

az network dns record-set a update --resource-group myresourcegroup --zone-name contoso.com --name www --set ttl=60

To modify the metadata of an existing record set

Record set metadata can be used to associate application-specific data with each record set, as key-value pairs. To modify the metadata of an existing record set, use az network dns record-set <record-type> update. For help, see az network dns record-set <record-type> update --help.

The following example shows how to modify a record set with two metadata entries, "dept=finance" and "environment=production". Any existing metadata is replaced by the values given.

az network dns record-set a update --resource-group myresourcegroup --zone-name contoso.com --name www --set metadata.dept=finance metadata.environment=production

Delete a record set

Record sets can be deleted by using the az network dns record-set <record-type> delete command. For help, see azure network dns record-set <record-type> delete --help. Deleting a record set also deletes all records within the record set.