A fence has three stakes, and a hero has three gangs. Behind success, we need friends to bring us material or spiritual assistance. DNS is no exception. It is very important, so we need helpers or sharp tools. nslookup is a very important tool that can help us understand DNS very well. nslookup is integrated in Windows NT/2000/XP/2003. It is a command line tool that monitors whether the DNS server in the network can correctly implement domain name resolution. To use it normally, you must confirm that the TCP/IP protocol has been installed on the system. For its related information, we can view it in the command prompt interface, enter "nslookup" and press Enter, and then run the "?" command.
We often encounter many problems when using the Internet. One of the more common problems is that the web page cannot be opened. Some of these problems are caused by DNS failures, and some are caused by other reasons. When does it become a DNS problem? How to confirm whether there is a problem with DNS? If so, how to solve it? This time we will use nslookup.
Under normal circumstances, either the DNS server is not working properly, or the site we visit does not appear in the DNS server resolution database, that is, it cannot resolve the IP address of the domain name, and naturally cannot be accessed. Let's take a look at how these problems are reflected in nslookup.
1. DNS server is not working properly
Enter "cmd" in "Start → Run" to open the command prompt window and enter "nslookup dns.qy.com.cn". If the DNS server is working normally, we will see the return information as shown in the figure (see Figure 1 ).
Among them, Server is the domain name of the DNS server you are using, Address represents the IP address of the DNS server, and the Name displayed next represents the name of the query domain name. Multiple IP addresses appear in Addresses, which proves that the domain name is bound to multiple servers. If Aliases appears, it is the alias of the domain name.
When the DNS server is not working properly, we will receive Can't find server name for domain: No response from server
Or: *** Defualt servers are not available
Server: Unknown
Address: 127.0.0.1
2. The DNS server cannot resolve the accessed domain name
Sometimes the DNS server may be working normally, but you will receive the sentence "can't find ***: Non-existent domain" ("***" indicates the domain name to be queried), which means that the DNS server cannot resolve normally. This domain name may be blocked. (Source: http://dns.qy.com.cn )