Alibaba Cloud DNS:Subdomain Management

Subdomain delegation

By default, the entire primary domain (such as example.com) uses one set of NS servers for DNS resolution. However, the DNS standard lets you assign a separate set of NS records to a subdomain. This is called subdomain delegation. For example, abc.example.com can use a different set of NS servers than its parent domain. Its control and DNS rules become fully independent. If you are not familiar with primary domains and subdomains, read the domain hierarchy.

Scenarios

Distributed business isolation and O&M autonomy

• SaaS providers, multi-line-of-business enterprises, and conglomerates often have separate O&M teams for each business. Each team can manage DNS for product.example.com without affecting the primary domain or other subdomains.

• You can manage DNS resources for the staging environment test-env.example.com separately. This prevents accidental changes from affecting production in the primary domain.

Decoupling across clouds, data centers, or CDN platforms

• Government, enterprise, and finance customers often run their own DNS servers. However, building and maintaining them is expensive. You can delegate a subdomain to Alibaba Cloud DNS for standalone management.

• Your primary domain uses a third-party DNS provider. You cannot migrate all DNS records to Alibaba Cloud DNS immediately. Instead, start by migrating only the subdomain to Alibaba Cloud DNS.

Primary domain uses a third-party DNS provider. Subdomain uses Alibaba Cloud DNS.

1. Go to the Alibaba Cloud DNS – Public Authoritative DNS page. Click Add Zone.

2. In the Add Zone dialog box, enter the subdomain—for example, demo.example.com. Click Verify TXT Record.

   

3. In the domain registrant verification dialog box, copy the host record and record value.

   

4. Go to your third-party DNS provider. On the primary domain’s DNS settings page, add a TXT record using the host record and record value from the domain registrant verification step.

5. Return to the dialog box from step 3. Click Verify. The TXT verification passes.

   Important

   Registrant identity verification lets you copy the Hostname and Record Value. Before you click the Verify button, you can close this dialog box. The Record Value for TXT record validation is valid for 1 day. If you click Verify, you can perform validation up to three times. If all three attempts fail, the TXT record value is reset. After you add the TXT record to the root domain, click the Verify button to perform TXT validation.

6. The subdomain appears in the DNS record list. View the DNS Server IP Address for the subdomain. This is the DNS address that Alibaba Cloud DNS assigned to it.

   

7. (Optional) Skip this step if the subdomain has no active DNS records. If the subdomain already has active DNS records, add them again in Alibaba Cloud DNS before continuing.

8. Go to your third-party DNS provider. On the primary domain’s DNS settings page, add an NS record for the subdomain. Point it to the DNS server addresses that Alibaba Cloud DNS assigned to the subdomain. For example, if your subdomain is test.example.com:

   Host record	Record type	Record value
   test	NS	ns1.alidns.com
   test	NS	ns2.alidns.com

Both primary domain and subdomain use Alibaba Cloud DNS.

The primary domain and subdomain can belong to different Alibaba Cloud accounts—or the same Alibaba Cloud account.

1. Go to the Alibaba Cloud DNS – Public Authoritative DNS page. Click Add Zone.

2. In the Add Zone dialog box, enter the subdomain. Click Verify TXT Record.

3. In the Registrant Verification dialog box, copy the Hostname and Record Value.

   Important

   Registrant identity verification lets you copy the Hostname and Record Value. Before you click the Verify button, you can close this dialog box. The Record Value for TXT record validation is valid for 1 day. If you click Verify, you can perform validation up to three times. If all three attempts fail, the TXT record value is reset. After you add the TXT record to the root domain, click the Verify button to perform TXT validation.

4. Log in to the Alibaba Cloud account that owns the primary domain. Go to the DNS settings page. Add a TXT record using the Hostname and Record Value from the domain registrant verification step.

5. After the TXT record takes effect, return to the Registrant Verification dialog box from step 3. Click Verify.

6. After the TXT verification passes, add the subdomain. The subdomain appears automatically in the DNS record list. Click the subdomain to open its DNS settings page. Alibaba Cloud DNS automatically syncs DNS records for the subdomain from the primary domain. For full sync rules, see Sync rules for DNS records when both primary and subdomains use Alibaba Cloud DNS.

7. The subdomain appears in the DNS record list. View the DNS Server IP Address for the subdomain. This is the DNS address that Alibaba Cloud DNS assigned to it.

   

8. If the primary domain has DNS records for the subdomain, those records stop working after you delegate the subdomain. Delete them from the primary domain. Then configure DNS records on the subdomain’s DNS settings page. Skip this step if the primary domain has no subdomain records.

   Important

   The primary domain and subdomain must use the same edition of Alibaba Cloud DNS. For example, if the primary domain uses the paid edition, the subdomain must also use the paid edition. If the primary domain uses the paid edition, first bind the subdomain to the paid edition. Then add the NS records on the primary domain.

Recover a subdomain

If another Alibaba Cloud account added your subdomain as a managed subdomain, use the Retrieve Zone feature to move management rights and DNS records back to your current account.

1. Go to the Alibaba Cloud DNS – Public Authoritative DNS page. Click Add Zone.

2. In the Add Zone dialog box, enter the subdomain. Click Retrieve Zone.

3. In the Registrant Verification dialog box, copy the Hostname and Record Value.

   Important

   Registrant identity verification lets you copy the Hostname and Record Value. Before you click the Verify button, you can close this dialog box. The Record Value for TXT record validation is valid for 1 day. If you click Verify, you can perform validation up to three times. If all three attempts fail, the TXT record value is reset. After you add the TXT record to the root domain, click the Verify button to perform TXT validation.

4. After domain registrant verification passes, the subdomain and its DNS records appear automatically in your account.

Delete a subdomain

If you no longer need to manage a subdomain separately, delete it. All DNS records under the subdomain are deleted permanently.

1. Go to the Alibaba Cloud DNS – Public Authoritative DNS page. In the Actions column, click Delete.

   

Sync rules for DNS records when both primary and subdomains use Alibaba Cloud DNS

After you add a subdomain, any DNS records for that subdomain on the primary domain are synced automatically. Records added to the primary domain after you add the subdomain are not synced. Full rules follow.