How to Diagnose DNS Error with Ax3soft Unicorn

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What is DNS?

The Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most prominently, it translates domain names, which can be easily memorized by humans, to the numerical IP addresses needed for the purpose of computer services and devices worldwide. The Domain Name System is an essential component of the functionality of most Internet services.

Reason to can not visit web

Many reason can lead to can not visit web, but there are only two direct reason:

a. The web host is abnormal, that leads to it can’t be visited.

b. A DNS server is abnormal, that leads to a web isn’t visited.

When a Web can’t be visited,  People often think that the web host is abnormal, however, ignoring the second reason.

How to Diagnose DNS Error with Ax3soft Unicorn

Today , I encountered such a case. I’ll share with you the experience. It’s very ease to find out the reason.

Step1: Find out the IP address of the web host and ping it, checking the response, if you are getting a response then your IP connectivity is fine with remote hosts.

Step2: Try pinging domain and check the response, if the DNS server is abnormal, you will see the response to request time out.

Step3: When the DNS server is abnormal, we will can’t get response which come from DNS server. So a lot of DNS request packets will be captured, however, the response packet are few, please see the figure below:

Figure 1:  How to Diagnose DNS Error  in the  Summary tab

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