When a backend server fails, DNS resolution continues directing traffic to the unavailable address. Health Check uses Global Traffic Manager 3.0 (GTM) to monitor server availability. When GTM detects an unhealthy server, it automatically reroutes DNS traffic to a healthy address, providing failover without manual intervention.
Enabling health check creates an Access Domain in Global Traffic Manager 3.0. Be aware of these changes before proceeding:
GTM takes over DNS resolution with intelligent routing. Authoritative zone DNS records stop taking effect while the Access Domain is active. After you disable or delete the Access Domain, the domain reverts to authoritative zone resolution.
Health check uses Global Traffic Manager 3.0 on a pay-as-you-go basis. For pricing details, see Billing.
After enabling, add, modify, or delete IP addresses in the Global Traffic Manager 3.0 address pool, not in the authoritative zone DNS records.
To disable health check, go to the Global Traffic Manager 3.0 console and disable or delete the corresponding Access Domain. Authoritative zone DNS records then take effect again.
Prerequisites
Before you begin, make sure that:
The DNS record type is
A,AAAA, orCNAME. Other record types are not supported.Backend servers or network devices allow ICMP requests. If a firewall blocks the ICMP protocol, health check always reports failure.
One-click setup uses ICMP (ping) detection by default. To add port-level or application-layer detection, configure detection templates after creating an Access Domain.
Enable health check
Open the Alibaba Cloud DNS - Public Zone console. Find the target domain and open its management page.
Select the Settings tab. The Health Check option appears in the Actions column for A, AAAA, and CNAME records.
Click Health Check in the Actions column for the target DNS record. A confirmation dialog appears with the following options:
Interval: Choose a probe frequency: 15 Seconds, 1 Minute, 5 Minutes, 15 Minutes, 30 Minutes, or 60 Minutes.
Record Value Check: Select which record values to monitor. The system generates one Access Domain per record set. All lines for the same domain and record type share an Access Domain. Enable or disable monitoring for each line individually.
Submit the form. The system creates the Access Domain and begins monitoring record values using ICMP (ping). Global Traffic Manager 3.0 handles DNS resolution from this point.
After setup, the DNS record's Hostname column displays a
GTMtag. This indicates that GTM-based resolution is active.
While health check is enabled, GTM policies control DNS resolution. Authoritative zone DNS records do not take effect. After you disable or delete the Access Domain, the domain reverts to authoritative zone resolution.
Billing
Health check uses Global Traffic Manager 3.0 on a pay-as-you-go basis. Costs consist of four components. For full pricing details, see Billing.
Billable item | Price | Description |
Domain Name Count | USD 0.015/domain name/day | Based on the number of Access Domain entries (both enabled and disabled). Settled daily. |
DNS Query Count | USD 0.004/10,000 requests | Based on the number of DNS queries that GTM processes. Settled daily. |
Health Probe Count | USD 1.5/10,000 checks | Based on the number of health checks performed on addresses. Settled daily. |
SMS Alerts | USD 0.225/message | Based on the number of alert messages sent. Settled daily. |
Disabling an Access Domain does not stop health check tasks from running. To stop billing completely, delete the health check tasks.
Cost estimation example
Consider a setup with the following parameters:
1 Access Domain
2 IP addresses
3 detection nodes
HTTP detection on 2 ports (such as 80 and 3000) per IP address
Probe frequency: once per minute
Average of 100,000 DNS resolution requests per day
1 SMS alert per day
Estimated monthly cost:
Access domain fee: 1 domain name x USD 0.015/day x 30 days = USD 0.45
Health check fee: 2 IPs x 2 ports x 3 nodes x 1 check/min x 60 min x 24 hr x 30 days x USD 0.00015/check = USD 77.64
DNS resolution request fee: 100,000 requests/day x 30 days x USD 0.004/10,000 requests = USD 1.20
SMS alert fee: 1 message/day x 30 days x USD 0.225/message = USD 6.75
Total: USD 86.04/month
Modify DNS records
After enabling health check for a DNS record, manage addresses through the Access Domain in Global Traffic Manager 3.0. For details, see Address pool configuration and Address configuration.
To edit the authoritative zone record value used for fallback resolution (after disabling health check):
Open the Alibaba Cloud DNS - Public Zone console. Find the target domain and open its management page.
Select the Settings tab. Find the target DNS record and click Edit.
Review the risk notification in the dialog, then click OK.
Disable health check
To stop using health check, disable or delete the Access Domain. DNS resolution then reverts to authoritative zone records.
Open the Alibaba Cloud DNS - Global Traffic Manager console.
Toggle the switch to disable the Access Domain.
To stop using Global Traffic Manager 3.0 entirely, click Delete in the Actions column to remove the Access Domain.