DNS

Overview

DNS is both simple and complex.

DNS translates the human domains into something computers can understand.


skynet  IN A     193.1.96.165
*.users IN CNAME skynet

It can also provide useful information.


skynet.ie. IN TXT   "v=spf1 a:mail.skynet.ie -all"

Structure

DNS is hierarchical and delegated.

Root servers

TLD (Top Level Domain) servers (.ie, .com, .eu)

Domain servers (skynet.ie)

We run our own DNS servers, Bind9 (ns1.skynet.ie, ns2.skynet.ie)

We also have control over csn.ul.ie and ulcompsoc.ie

Viewing DNS records

On the nixos repo:


colmena build --keep-result --on vendetta
cat .gcroots/node-vendetta/etc/skynet/dns/skynet.ie

On top of that we also manage the reverse DNS (rDNS)

Reverse DNS allows you to look up and IP and get the domains.


cat .gcroots/node-vendetta/etc/skynet/dns/64-64.99.1.193.in-addr.arpa

To validate them there is this tool: https://bind.jamiewood.io/
(put skynet.ie in teh FQDN box)

Commands


dig skynet.ie
dig skynet.ie @1.1.1.1
dig skynet.ie @ns1.skynet.ie
host 193.1.99.75

Use this time to explore the nixos repo to explain

  • https://forgejo.skynet.ie/Skynet/nixos/issues/21
  • https://forgejo.skynet.ie/Skynet/nixos/issues/33