Building a DNS Server

Jonathan Leeming

Building a DNS Server

What is DNS?

Domain Name System

Request Structure


Responce/Resource Records

DNS Records

DNS records contain information about a domain, such as its IP address or mail server.

DNS Zones

DNS Zones are administrative units that contain DNS records for a domain or a subdomain.

Label Compression

Used to represent domains, if part of the domain has already been referenced earlier, we can use a pointer to it.


example.com.          512   IN  A
steam.example.com.   1024   IN  TXT  Let's go GAMERS!

We repeat example.com.. The server can just send a pointer to the first instance of example.com. and clients parse from there.

DNS Caching

DNS caching involves storing previously resolved DNS queries to speed up future lookups.

DNS Security

DNS Security mechanisms protect against various threats, including DNS spoofing and cache poisoning.

Building a DNS Server — GPT Style

  1. Download the DNS server template
  2. Set up a basic DNS server
  3. Handle DNS queries
  4. Implement DNS records
  5. Manage DNS Zones
  6. Implement DNS caching
  7. Enhance DNS security
  8. Handle DNS requests from different clients
  9. Troubleshoot DNS issues

Building a DNS Server

  1. Download the DNS server template
  2. Parse a DNS request
  3. Create a response
  4. Send the response
  5. Implement request recursion