Use ping and traceroute to troubleshoot network connectivity issues. 1. Use ping to check basic connectivity. If you return "64 bytes from..." to indicate network access, it may be disconnected if "Request timed out" is displayed; 2. Use traceroute to view the routing path. A certain hop is an asterisk, which may be a node failure or a firewall blocking; 3. First, the public network IP is tested and then the domain name is tested to determine whether the DNS is normal; 4. Use the two to analyze the overall connectivity and specific failure points; 5. Note that it is normal for some nodes to not respond to ICMP, and you need to try several times to avoid misjudgment.

When testing network connectivity, ping and traceroute are the two most commonly used and basic command line tools. They can help you quickly determine whether the network is smooth and where something goes wrong.

Check basic connectivity with ping

The purpose of ping is to send an ICMP request packet to the target host and wait for a response. It can be used to determine whether the network between the local and the target is connected.

How to use:

Enter:

 ping example.com

Or ping the IP address directly:

 ping 8.8.8.8

How do you see the results?

• If you return information like "64 bytes from...", it means that the network is connected.
• If "Request timed out" or "Destination Host Unreachable" is always displayed, it may be that a link in the middle is broken.
• Pay attention to the packet loss rate and delay time. These two indicators can help you initially judge network quality.

Small suggestions:

• Start ping from the public network address (such as 8.8.8.8) and confirm that there is no problem with the local exit;
• Try ping the domain name again to see if DNS resolves normally;
• If the domain name can be resolved but does not work, it means that DNS is fine, but there may be a problem with the network.

Use traceroute to view the route path

The purpose of traceroute is to show every hop that the data packet passes from your computer to the target server. It can help you locate the specific node where network failure occurs.

How to use:

Enter:

 traceroute example.com

Windows users use tracert :

 tracert example.com

How do you see the results?

• Each row represents an intermediate node and usually displays three rounds of test results.
• If a row is full of asterisks ( *), indicating that the node is not responding or is blocked by a firewall.
• If all the subsequent nodes timed out and the previous one was normal, it is very likely that something was wrong with that node.

Common phenomena:

• The 5th jump starts to time out, and then all do not work → The problem may be on the 5th jump device.
• A hop delay suddenly becomes much larger in the middle → There may be network congestion or link instability.

Using ping and traceroute is more effective

You can know whether it can be done by using ping alone, but you don’t know where it can’t be done; you can see the path using traceroute alone, but you don’t necessarily know where it is stuck. Only by combining the two can we locate the problem more accurately.

The troubleshooting process can be as follows:

• First use ping to determine whether the whole is successful;
• If it doesn't work, use traceroute to see which jump is stuck;
• After finding the exception node, further contact the ISP or service provider to confirm the situation.

Note:

• Some nodes do not respond to ICMP requests by default, so it does not mean they are really broken;
• Sometimes the paths taken by different routes may vary;
• Try a few more times to avoid occasional problems interfering with judgment.

Basically these are the operations. Although it seems simple, it is very practical when troubleshooting network problems. As long as you master the basic usage and analysis ideas of these two tools, most common network connection problems can be quickly located.

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