Access domain names_Global Traffic Manager 3.0 - Alibaba Cloud DNS

The Get started topic provides a scenario-based example of how to configure and use Global Traffic Manager 3.0. This topic describes the detailed steps to configure an Access Domain.

Overall process

Create Access Domain

Preparations

Select a billing method. If you select the subscription billing method, you must purchase a subscription instance in advance.
An Access Domain depends on a domain name hosted in a Public Zone. Ensure that the Public Zone contains at least one domain name whose DNS Server IP Address status is Available.

Procedure

Go to the Alibaba Cloud DNS - Global Traffic Manager console and click Create Access Domain.
In the dialog box that appears, select a scenario. You can choose from a list of common scenarios or select Custom Scenario.
Click the Access Domain icon and then click Basic Configuration.

Complete the form. The following table describes the parameters.

Parameter	Description
Access Domain	An access domain name consists of a `host record` and a `domain name`. Host Record: You can customize the host record, such as `gtm`. Domain Name: Select a domain name that is hosted by the public authoritative zone and whose DNS Server IP Address is Available.
Billing Method	Options: Subscription and Pay-as-you-go.
Bind Instance	If you select Subscription as the billing method, you must bind a GTM instance that you purchased in advance.
Record Type	The record type of the address pool that requires smart scheduling. Supported record types are A, AAAA, and CNAME. The corresponding address pool types are IPv4, IPv6, and Domain Name.
TTL (Seconds)	GTM provides traffic management services in the form of domain names. The global TTL is the amount of time that the DNS record, which resolves the Access Domain to an address, is cached on a carrier's local DNS server.
Enabed State	The status of the domain name instance. The instance is disabled by default. In this state, the GTM policies do not take effect and no DNS resolution is provided. We recommend that you complete the configuration of address pools, addresses, and load balancing policies before you enable the instance and connect it for resolution. Important If your Access Domain already has a DNS record of the same type in Authoritative DNS, the DNS record in Authoritative DNS becomes invalid after you enable the Access Domain. The smart resolution configured in GTM takes precedence.
Remarks	A user-defined identifier to help you remember and identify the application service under this instance.

After the access domain name is created, it appears in the Access Domain list.

Configure an address pool

Important

The record type of the Access Domain determines the available Type. The mappings are as follows:

Access Domain's Record Type	Address pool type
A	IPv4, Domain Name
AAAA	IPv6, Domain Name
CNAME	Domain Name

Add Address Pool

On the Access Domain configuration page, click the Access Domain icon and then click Add Address Pool.
In the panel that appears, configure the parameters. For more information about the parameters, see 2. Configure an address pool.

Select Address Pool

On the Access Domain configuration page, click the Access Domain icon and then click Select Address Pool.
Select an existing address pool. The list displays only address pools that match the Record Type of the Access Domain. You can select multiple address pools at a time.

Enable, disable, or delete an Access Domain

Impact of changes

Change Type	Impact
Enable	Confirm that the Access Domain is configured correctly and the Service Availability is Available. Otherwise, DNS resolution exceptions may occur. If a domain name record with the same name and type exists in the Public Zone, the system first follows the GTM policy to intelligently schedule and parse queries for that record to implement advanced features such as traffic load balancing or failover.
Disable/Delete	The domain will revert to using the Public Zone for DNS resolution. Incorrectly configured DNS records for the Public Zone may cause DNS resolution errors and service interruptions. Please proceed with caution. After you disable or delete an Access Domain, you may still be able to query the DNS records for the Access Domain. This is because the DNS servers of local carriers maintain a cache. As long as the cache has not expired, the servers will not request the latest DNS records from Alibaba Cloud DNS. Instead, they will directly return the locally cached DNS records to visitors. Therefore, the changes take effect only after the carriers refresh their local caches. The time it takes for the changes to take effect primarily depends on the TTL of the DNS records in the carriers' DNS caches. The changes are expected to take effect in approximately 10 to 30 minutes.

Procedure

On the Access Domain configuration page, click the Access Domain icon and then click Enabled, Disabled, or Delete.
In the confirmation dialog box that appears, confirm the operation.

Description of Access Domain statuses

Description of Health Status

Normal: All address pools referenced by the Access Domain are available.

Warning: Some of the address pools referenced by the Access Domain are unavailable. In the Warning state, DNS resolution continues for available address pools but stops for unavailable address pools.

Abnormal: All address pools referenced by the Access Domain are unavailable.

Description of Service Availability

The Service Availability is determined by the Enabed State and the Health Status. The logic is as follows:

Enabed State	Health Status	Service Availability
Enabled	Normal or Warning	Available
Enabled	Abnormal	Unavailable (Underlying Resolution Being Performed) In this state, GTM performs failover resolution to return a resolution result to the client whenever possible. Important Failover resolution rules: If an address pool for a specific line becomes unavailable, GTM responds with an address from an available address pool that is associated with the global default line and has the lowest sequence number. If all address pools for all lines are unavailable, GTM responds with addresses from the non-empty address pool that has the lowest sequence number. All addresses in the address pool are returned in a round-robin manner.
Disabled	Normal or Abnormal	Unavailable