Unable to Establish Connection with Server (2)
The first is to analyze possible problems on the client:
1.
Analysis method: If it is hijacked, confirm with the customer whether the Host accessed by Probe belongs to the customer. Because if it is directly hijacked to a ErrorIP, this IP is likely to be invalid (after all, the scammer will not open the website for too long)
2.
Analysis method: Instant Testing takes a screenshot. Some information can be seen from the screenshots of many actively blocked websites.
You can try adding host Instant Testing to see if you can access it. Some firewalls will block domain names.
3.
Analysis method: Look at the Probe error reported and the Network delay in executing Ping to see if it is Critical (needs to be enabled in task settings). If there is a packet capture, you can check the packet capture.
Next, let’s analyze whether there is a problem with the operator:
1.
The principles of ping and trace are the same, except that trace can see the Network delay of each layer of equipment.
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4.
It should be noted that if the Trace is passed, it can only mean that Network is smooth. Ping is implemented by the ICMP protocol and is the Network layer (IP layer). Page access is through ports 80 and 443, which is implemented by the TCP layer. If the IP layer is passed, the TCP layer will continue to check.
Finally, let’s analyze whether there is a problem on the server side:
1.
Generally, if the problem is Host, the quantity ratio will not be too low. And there will be a concentrated high incidence in a certain period of time.
2.
Generally, customers will purchase CDN services, so if there is no problem at the origin site, the problem should be concentrated, or the problem should occur repeatedly in a certain area.
3.
When the traffic usage of Host is too high or the occupancy of Memory is too high, Host has the practice of actively discarding packets to reduce the pressure on the server.