What are alert logs?
Alert logs are generated by Global Traffic Manager (GTM) in the following situations: a. The health check feature detects abnormal addresses or the abnormal addresses become available. b. Address pool sets become unavailable or available. c. Primary and secondary address pools are switched over.
Overview
The health check feature detects abnormal addresses
Alert logs are generated if the health check feature detects abnormal addresses. Each log entry includes the time when an error occurs, an abnormal address, and an error code. You can identify the cause based on the error code. The following table describes common error codes.
Protocol | Status code | Description |
HTTP | 610 | The error code returned because the connection or the Secure Sockets Layer (SSL) certificate exchange timed out. The timeout period is 30s. |
613 | The error code returned because an error occurred during DNS resolution. | |
615 | The error code returned because the expected content is not found in the response. | |
616 | The error code returned because the authentication failed. | |
611 | The error code returned because the monitoring failed due to other causes. | |
Ping | 550 | The error code returned because the network connection failed. |
610 | The error code returned because no response was returned within 2s for any of the packets that were sent. | |
613 | The error code returned because the hostname failed to be resolved to an IP address. | |
TCP | 550 | The error code returned because the socket failed to be opened. This error occurs when system resources are insufficient. |
610 | The error code returned because no response was returned or the response timed out. | |
611 | The error code returned because the connection timed out or was rejected. | |
615 | The error code returned because the expected content is not found in the response. | |
UDP | 550 | The error code returned because the socket failed to be opened. This error occurs when system resources are insufficient. |
611 | The error code returned because the hostname failed to be resolved and the connection failed. | |
610 | The error code returned because the request failed to be sent or the response failed to be received. | |
615 | The error code returned because the expected content is not found in the response. | |
DNS | 610 | The error code returned because an error occurred during DNS resolution. |
613 | The error code returned because the DNS query failed. | |
615 | The error code returned because the expected content is not found in the response. |
Unavailable addresses become available
Alert logs are generated if the health check feature detects that unavailable addresses in an address pool set become available. Each log entry includes the recovery time and the addresses.
Address pool sets become unavailable
If the number of available addresses in an address pool set is less than the value of Minimum Available Addresses, GTM determines that the address pool set is unavailable. A log entry is generated in this case. Each log entry includes a specific time, the name of an address pool set, the name of an access policy, an address pool type, and the minimum number of available addresses.
Unavailable address pool sets become available
If the number of available addresses in an address pool set is greater than or equal to the value of Minimum Available Addresses, GTM determines that the address pool set is available. A log entry is generated in this case. Each log entry includes a specific time, the name of an address pool set, the name of an access policy, an address pool type, and the minimum number of available addresses.
Primary and secondary address pool sets are switched over
If a primary address pool set that is associated with an access policy is unavailable, GTM switches to a secondary address pool set. A log entry is generated in this case. Each log entry includes a specific time, the name of an access policy, and the switchover between the primary address pool set and the secondary address pool set.
Procedure
Log on to the Alibaba Cloud DNS console.
In the left-side navigation pane, click Global Traffic Manager. On the Global Traffic Manager page, click the ID of the instance that you want to manage. On the Basic Settings page, click the Alert Logs tab.
If you want to query the meanings of the HTTP status codes, click HTTP Status Codes Returned for Health Checks in the upper-right corner of the Alert Logs page.