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title = "Skynet: DNS"
date = 2023-10-14
slides = true
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# DNS
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## Overview
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DNS is both simple and complex.
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DNS translates the human domains into something computers can understand.
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```dns
skynet IN A 193.1.96.165
*.users IN CNAME skynet
```
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It can also provide useful information.
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```dns
skynet.ie. IN TXT "v=spf1 a:mail.skynet.ie -all"
```
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## Structure
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DNS is hierarchical and delegated.
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Root servers
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TLD (Top Level Domain) servers (``.ie``, ``.com``, ``.eu``)
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Domain servers (``skynet.ie``)
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We run our own DNS servers, Bind9 (``ns1.skynet.ie``, ``ns2.skynet.ie``)
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We also have control over ``csn.ul.ie`` and ``ulcompsoc.ie``
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## Viewing DNS records
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On the nixos repo:
```bash
colmena build --keep-result --on vendetta
cat .gcroots/node-vendetta/etc/skynet/dns/skynet.ie
```
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On top of that we also manage the reverse DNS (rDNS)
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Reverse DNS allows you to look up and IP and get the domains.
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```bash
cat .gcroots/node-vendetta/etc/skynet/dns/64-64.99.1.193.in-addr.arpa
```
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To validate them there is this tool: <>
(put ``skynet.ie`` in teh FQDN box)
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## Commands
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```bash
dig skynet.ie
dig skynet.ie @1.1.1.1
dig skynet.ie @ns1.skynet.ie
host 193.1.99.75
```
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//Use this time to explore the nixos repo to explain//
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* <>
* <>