Categorygithub.com/biswaone/dns-go
repositorypackage
0.0.0-20250121163523-3966f7149196
Repository: https://github.com/biswaone/dns-go.git
Documentation: pkg.go.dev
Overview
Dependencies
9
Dependents
0

# README

DNS Resolver

A simple DNS resolver implemented in Go that demonstrates how DNS resolution works from the ground up. This program performs recursive DNS resolution starting from a root nameserver, similar to how a DNS resolver works in practice.

Features

  • Performs recursive DNS resolution
  • Supports A (address) and NS (nameserver) record lookups
  • Handles DNS message encoding and decoding
  • Follows the DNS protocol specification
  • Starts from root nameserver (198.41.0.4) and traverses the DNS hierarchy

Prerequisites

  • Go 1.15 or higher
  • Basic understanding of DNS concepts

Installation

  1. Clone the repository:
git clone https://github.com/biswaone/dns-go
cd dns-go
  1. Build the program:
go build

Usage

Run the program with a domain name and record type as arguments:

./dns-go <record_type> <domain_name>

Where:

  • <domain_name> is the domain you want to look up (e.g., example.com)
  • <record_type> is either "A" or "NS" (case-insensitive)

Examples

Look up an A record (IP address):

./dns-go A example.com

Look up an NS record (nameserver):

./dns-go NS example.com

Sample Output

For A record lookup:

Querying 198.41.0.4 for example.com
Querying 192.41.162.30 for example.com
Querying 198.41.0.4 for a.iana-servers.net
Querying 192.55.83.30 for a.iana-servers.net
Querying 199.43.135.53 for a.iana-servers.net
Querying 199.43.135.53 for example.com
The IP of example.com is 23.192.228.80

For NS record lookup:

Querying 198.41.0.4 for example.com
Querying 192.41.162.30 for example.com
Querying 198.41.0.4 for a.iana-servers.net
Querying 192.55.83.30 for a.iana-servers.net
Querying 199.43.135.53 for a.iana-servers.net
Querying 199.43.135.53 for example.com
The nameserver for example.com is a.iana-servers.net

How It Works

  1. The program starts with a root nameserver (198.41.0.4)
  2. It sends a DNS query for the requested domain and record type
  3. If the nameserver doesn't have the answer, it returns:
    • Either the IP of a more specific nameserver
    • Or the domain name of a more specific nameserver
  4. The program follows these referrals until it gets the final answer
  5. For NS queries, it returns the authoritative nameserver
  6. For A queries, it returns the IP address

Acknowledgments