Each site monitoring protocol returns a status code during the detection process. Common status codes are described as follows.

Definitions of custom status codes of CloudMonitor

Protocols  Status code Description 
HTTP 610 Timeout (connection timeout, SSL Certificate exchange timeout, 30 s)
HTTP 613 DNS resolution Error
HTTP 615 The content does not match
HTTP 616 An error occurred while performing the authentication.
HTTP 611 Detection failure due to other reasons
HTTP 617

Maximum jump count exceeded

The Max number of 3xx Redirects allowed at the ECS probe point is 5 times

The maximum number of 3xx redirected jumps allowed by the carrier probe point is 2

HTTP 703 The internal network detection of the server is prohibited. The internal network probe can use the availability monitoring function.
Ping 550 Network is not available
Ping 610 All sent packets receive no response in 2 seconds despite stable network condition.
Ping 613 |Failed IP address resolution based on the host file|
Ping 703 The internal network detection of the server is prohibited. The internal network probe can use the availability monitoring function.
TCP 550 |Failed to enable the socket. A typical cause is that the system sources have run out.|
TCP 610 |Failed response reception (time-out or no response)|
TCP 611 Failed connection (time-out or rejected by the peer end)|
TCP 615 The content does not match
TCP 703 The internal network detection of the server is prohibited. The internal network probe can use the availability monitoring function.
UDP 550 |Failed to enable the socket. A typical cause is that the system sources have run out.|
UDP 611 Failed connection (failed resolution based on the host file)|
UDP 610 |Failed sending or reception|
UDP 615 The content does not match
UDP 703 The internal network detection of the server is prohibited. The internal network probe can use the availability monitoring function.
DNS 610 DNS resolution failed
DNS 613 |DNS query communication error|
DNS 615 The content does not match
DNS 703 The internal network detection of the server is prohibited. The internal network probe can use the availability monitoring function.
SMTP 610 Connection time-out
SMTP 611 Your site could not be accessed successfully, failure Reasons include, but are not limited to, DNS resolution failure, Incorrect email format, failed to initialize SMTP client, and so on
SMTP 616 Login denied
SMTP 703 The internal network detection of the server is prohibited. The internal network probe can use the availability monitoring function.
POP3 611 Unable to successfully access your site
POP3 703 The internal network detection of the server is prohibited. The internal network probe can use the availability monitoring function.
FTP 610 FTP Transfer failed
FTP 611 Failure caused by other factors, such as failure of DNS resolution, failure of TCP connection, etc.
FTP 616 A RAM user fails to log on to the console
FTP 703 The internal network detection of the server is prohibited. The internal network probe can use the availability monitoring function.

Definitions of standard HTTP status codes

Status code Description Note
200 Request completed Status Codes 2XX indicate that the service is normal.
300 Multiple choices The server can perform multiple operations based on the request. The server selects one operation to perform based on the user agent, or provides a list of operations for the user agent to choose.
301 Moved permanently The requested webpage has been permanently moved to a new location. When the server returns Status Code 301 (in response to a GET or HEAD request), it automatically redirects the user agent to the new location. You must use this status code to notify Googlebot that a webpage or website has been permanently transferred to a new location.
302 Moved temporarily The server returns the response from a webpage in a different location, but the user agent must use the original location for subsequent requests. Similar to Code 301 in response to a GET or HEAD request, this code means that the server automatically redirects the user agent to a different location.
303 See other The server returns this code when the user agent must send GET requests separately for different locations for response retrieval. For all requests except HEAD requests, the server automatically jumps to other locations.
304 Not modified The requested webpage has not been modified since the last request. The webpage content is not returned when the server returns Status Code 304.
305 Use proxy The user agent can access the requested webpage only by proxy. If the server returns this code, it also specifies the proxy that the user agent must use.
400 Bad request The server does not understand the syntax of the request.
401 Unauthorized Authentication is required for the request. The server may return Status Code 401 in response to the webpage access request after logon.
403 Forbidden The server rejects the request.
404 Not found The server cannot find the requested webpage. For example, if the requested webpage does not exist on the server, the server returns Status Code 404.
405 Method not allowed The method specified in the request is forbidden.
406 Not acceptable The content characteristics of the request cannot be used to respond to the webpage access request.
407 Proxy authentication required This status code is similar to 401 (unauthorized), but it specifies that the user agent must use a proxy for authentication. If the server returns this code, it also specifies the proxy that the user agent must use.
408 The request times out. The server timed out waiting for the request.
409 Conflict A conflict occurred when the server completed the request. The server must include the conflict information in the response packet. The server may return Status Code 409 and provide a list of differences between two conflicting requests when responding to the PUT request that conflicts with the previous request.
411 Length required The server does not accept the request that contains header fields of invalid content length.
412 Precondition failed The server does not meet one of the preconditions that the user agent sets in the request.
413 Request entity too large The server cannot process the request because the request entity is too large and exceeds the server's processing capability.
414 Requested URI too long The server cannot process the request because the requested URI (usually the URL of the target website) is too long.
415 Unsupported media type The request format is not supported by the requested webpage.
416 Range not satisfiable The server returns this code if the request is out of the valid range of the requested webpage.
417 Expectation failed The server does not meet the requirements of the **Expect** request-header field.
499 Client closed request This status code is returned when the client closes the connection because it takes a long time for the server to process the request.
500 Internal server error The request cannot be completed due to a server error.
501 Not implemented This code is returned when the server does not have the function to complete the request. For example, when the server cannot identify the request method, it may return this status code.
502 Bad gateway The gateway or proxy server receives an invalid response from the upstream server.
503 Service unavailable The server is currently unavailable (due to overload or shutdown for maintenance). The unavailable state is temporary.
504 Gateway time-out The gateway or proxy server failed to receive requests from the upstream server in time.
505 HTTP version not supported The server does not support the HTTP version in the request.