Shulou(Shulou.com)06/01 Report--

This article will explain in detail how linux uses the dig command to mine domain name resolution information. The editor thinks it is very practical, so I share it with you as a reference. I hope you can get something after reading this article.

The command line tool dig is a powerful tool for domain name resolution and troubleshooting.

In terms of main functions, there is little difference between dig and nslookup, but dig is more like an enhanced version of nslookup, which can query some information managed by the domain name server, which is very useful when troubleshooting some problems. In general, dig is an easy-to-use and powerful command-line tool. (LCTT translation note: the main difference between dig and nslookup behavior is that dig uses the parsing library of the operating system itself, while nslookup uses the parsing library that comes with the program, which sometimes brings some behavioral differences. In addition, in terms of presentation, the dig return is the result returned in the format of BIND configuration information, with more technical details. )

The most basic function of dig is to query domain name information, so its name is actually an abbreviation for "domain name information query tool Domain Information Groper". The content that dig returns to the user can be very detailed or very concise, and the amount of content displayed is entirely determined by the options used by the user when querying.

I just need to check the IP address.

If you only need to query the IP address pointed to by a domain name, you can use the + short option:

$dig facebook.com + short31.13.66.35

When querying, it is found that some domain names will point to multiple IP addresses? This is actually a measure for the website to improve its usability.

$dig networkworld.com + short151.101.2.165151.101.66.165151.101.130.165151.101.194.165

It is precisely because these sites achieve high availability through load balancing, you may find that the order of these IP addresses is different in the next query. LCTT note: applications such as browsers use the first IP address returned by default, so this implements a simple load balancing. )

$dig networkworld.com + short151.101.130.165151.101.194.165151.101.2.165151.101.66.165 standard return

The standard return content of dig includes some information about the tool itself, as well as the response content returned when the domain name server is requested:

$dig networkworld.com; DiG 9.11.5-P4-5.1ubuntu2.1-Ubuntu > HEADER

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