Overview
dig is a flexible and powerful tool that allows users to send direct queries to DNS servers to obtain information about domains. Unlike `nslookup` or `host`, dig provides very detailed response results, separated into sections. This allows for clear verification of various types of DNS information, such as a domain's A records, MX records, and CNAME records. It is primarily used to test the behavior of DNS servers or diagnose domain configuration errors.
Key Features
The main features of the `dig` command are as follows:
- Can query specific DNS servers.
- Can query various types of DNS records (A, AAAA, MX, CNAME, etc.).
- Outputs detailed response results, divided into QUESTION, ANSWER, and AUTHORITY sections.
- Provides performance-related information, such as DNS server latency.
Sections of dig Output
dig's output is composed of several sections, which helps in clearly understanding the information.
- HEADER: Indicates basic information about the DNS query and response (ID, flags, etc.).
- QUESTION SECTION: Shows the domain and record type queried by the user.
- ANSWER SECTION: Contains the response information received from the DNS server. This includes the queried domain's IP address, etc.
- AUTHORITY SECTION: Shows the name server (NS) information that has authority over the query.
- ADDITIONAL SECTION: Provides additional information, such as the IP addresses of the name servers in the AUTHORITY SECTION.
Key Options
The main options of the `dig` command are grouped by purpose.
1) Query Options
2) Specify Record Type
3) Output Control
Generated command:
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Description:
`dig` Executes the command.
Combine the above options to virtually execute commands with AI.
Usage Examples
Learn the functionalities of the `dig` command through various usage examples.
Basic A Record Query
dig google.comQueries the A record for `google.com`. By default, it outputs the most detailed information.
Query A Record with Specific DNS Server
dig @8.8.8.8 google.comQueries the A record for `google.com` using Google's DNS server (`8.8.8.8`).
Concise A Record Query
dig +short google.comSuppresses all additional information and outputs only the IP address concisely. Good for scripting.
Query Mail Server (MX) Record
dig gmail.com MXQueries the mail server information for `gmail.com`.
Reverse IP Address Lookup
dig -x 8.8.8.8Performs a reverse lookup to convert the IP address `8.8.8.8` to a domain name.
Installation
dig is part of the `bind-utils` or `dnsutils` package. It is typically pre-installed on most systems, but if not, you can install it using the following commands.
Debian/Ubuntu
sudo apt update
sudo apt install -y dnsutilsRHEL/CentOS/Fedora
sudo dnf install -y bind-utilsArch Linux
sudo pacman -S --needed bindTips & Precautions
Here are some points to keep in mind when using the `dig` command.
Tips
- The default output of dig is very detailed; if you only need simple information, it's best to use the `+short` option.
- `nslookup` is no longer a recommended tool; it's better to use `dig` or `host` for DNS troubleshooting.
- When specifying a DNS server, use the `@` symbol, and you can use either an IP address or a hostname (e.g., `ns1.google.com`).