DNS resolution error troubleshooting

In the actual application process, you may encounter DNS resolution error, that is, when we access a domain name, we can't complete the work of parsing it to IP address, but input the website IP directly. Can be accessed normally, which is caused by the failure of DNS resolution. The probability of this phenomenon is relatively large, so this article will teach you some basic methods for troubleshooting DNS resolution from scratch. First, what is the DNS resolution failure? Generally speaking, like www.ccidnet.com we visit, these addresses are called domain names. It is well known that any host in the network is identified by an IP address, that is, only knowing the IP address of this site can be successfully implemented. Access operation. However, because the IP address information is not well remembered, the name of the domain name appears in the network. When accessing, we need to input the domain name of this good memory. There will be a server in the network that automatically resolves the corresponding domain name into an IP address. This is the DNS server. The machine that can implement the DNS resolution function can be either its own computer or a computer in the network, but when DNS resolution is wrong, for example, parsing a domain name into a wrong IP address, or not knowing the corresponding domain name at all. When the IP address is, we can't access the corresponding site through the domain name. This is the DNS resolution failure. The biggest symptom of DNS resolution failure is that there is no problem with accessing the IP address of the site. However, accessing his domain name will result in an error. Second, how to solve the DNS resolution failure: When our computer has a DNS resolution failure, do not worry, the solution is also very simple. (1) Use nslookup to determine whether it is really a DNS resolution failure: To be 100% judged whether it is a DNS resolution failure, it needs to be solved by the system's own NSLOOKUP. The first step: confirm that your system is windows 2000 and windows xp or higher operating system, and then enter "CMD" through "Start -> Run -> Enter and enter the command line mode. Step 2: Enter the nslookup command and press Enter to enter the DNS resolution query interface. Step 3: The command line window will display the DNS server address used by the current system. For example, the author's DNS server IP is 202.106.0.20. Step 4: Next enter the domain name of the site you are unable to access. For example, if the author enters www.ccidnet.com, if it cannot be accessed, then the DNS resolution should not be normal. We will receive a prompt message for DNS request timed out, timeout was 2 seconds. This shows that our computer does have a DNS resolution failure. Tip: If the DNS resolution is normal, it will feedback back to the correct IP address. For example, the author uses the address www.ccidnet.com to perform query analysis, and will get the information of name:ciidnet.com, addresses: 61.135.133.103, 61.135.133.104. . (2) Query whether the DNS server works normally: At this time, we have to look at the DNS address used by our computer and query his operation. The first step: confirm that your system is windows 2000 and windows xp or higher operating system, and then enter "CMD" through "Start -> Run -> Enter and enter the command line mode. Step 2: Enter the ipconfig /all command to query the network parameters. The third step: In the ipconfig /all display information we can see a place to write DNS SERVERS, this is our DNS server address. For example, the author is 202.106.0.20 and 202.106.46.151. From this address, it can be seen that it is an external network address. If there is a parsing error in the external network DNS, we can replace the other DNS server address to solve the problem. Step 4: If the internal network address of your company is displayed at the DNS server, then your company's DNS resolution is done to the internal DNS server. In this case, we need to check the DNS server in DNS. Perform nslookup operation on the server to see if it can be parsed normally. Solve the DNS service failure on the DNS server, and generally the problem can be solved. (3) Clear DNS cache information method: When the computer accesses the domain name, it does not need to seek help from the DNS server every time accessing. Generally, when the parsing work is completed once, the parsing entry will be saved in the computer's DNS cache list. If the DNS resolution changes at this time, the DNS cache list information will not be changed. When the computer accesses the domain name, the DNS server will not be connected to obtain the latest resolution information, and will be parsed according to the cache correspondence stored on the computer. This will cause a DNS resolution failure. At this point we should solve the problem by clearing the DNS cache command. Step 1: Enter the command line mode by "Start-> Run-> Enter CMD". Step 2: In the command line mode we can see that there is a parameter named /flushdns in ipconfig /?, this is the command to clear the DNS cache information. Step 3: Execute the ipconfig /flushdns command. When the prompt “successfully flushed the dns resolver cache” appears, the current computer cache information has been successfully cleared. Step 4: Next, when we access the domain name again, we will get the latest resolution address on the DNS server, and there will be no problem with the parsing error caused by the previous cache.

(4) Modify the HOSTS file method: Modifying the HOSTS method is to modify the DNS resolution correspondence in the HOSTS file to achieve the purpose of correct parsing. Because the HOSTS file in the local system is first viewed when the local computer accesses a domain name, the resolution relationship in the HOSTS file is greater than the resolution relationship on the DNS server. So when we want to bind a domain name to an IP address, we can do this by adding a parsing entry in the HOSTS file. Step 1: Go through “Start->Search” and look for the file named hosts. Step 2: Of course, readers who already know his path can go directly to the c:\\windows\\system32\\drivers\\etc directory to find the HOSTS file. If your system is Windows 2000, you should look in the c:\\winnt\\system32\\drivers\\etc directory. Step 3: Double-click the HOSTS file and select Open with the “Notepad” program. Step 4: After that we will see all the contents of the HOSTS file. By default, there is only one line of content "127.0.0.1 localhost". (Other lines with # in front are not real content, just help information.) Step 5: Add the entries you want to perform DNS resolution to the HOSTS file. The specific format is to write the IP address corresponding to the domain name first, then Space is connected to the domain name information. For example, the author added “211.153.80.1 www.ccidnet.com” and ““10.82.0.1 www.ccidnet.com” two entries. Step 6: After setting up, we will visit www.ccidnet.com and it will automatically analyze whether it is based on the internal network or the external network. Summary: Through the four steps described above, we can solve most of the DNS resolution problems. The first three of these methods are step by step to solve the DNS resolution fault step by step, and the last modified HOSTS file is There is really no way, a measure of expediency. Of course, no matter which method is used, we can solve the network failure caused by DNS parsing error.