A tiny DNS server that is capable of serving records configured in a MySQL table, or configured statically in a JSON file

• mode: Can be either db if your records are stored in a MySQL database, or static_records if your records are static and stored in the configuration JSON file.

• query_logging: Should the DNS server log queries made to it? Enable this if yes.

• db: The MySQL server & database credentials. This works only if mode is set to db

• listener: The listening/bind settings for the DNS server (usually has to be kept binding on port 53 to be able to accept DNS requests).

• process_unstored_dns_queries: Should the DNS server also accept queries of records that are not stored in your database table/static records configuration? Enable this if yes.

• static_records: Configure your static records here, one per JSON object. This works only if mode is set to static_records

1. Store your configuration file at /etc/simpledns/config.json You can copy the example configuration file and change it to serve your needs.
2. If running Simple DNS server in the db mode, use this database structure for your records table: https://github.com/oddmario/simple-dns-server/blob/main/db_structure.sql
3. Place the binary file of Simple DNS server at /usr/local/bin (e.g. /usr/local/bin/simpledns)
4. Make the binary file executable: chmod u+x /usr/local/bin/simpledns
5. Create a systemd service for the application. This can be done by creating /etc/systemd/system/simpledns.service to have this content:

[Unit]
Description=SimpleDNSserver

[Service]
User=root
WorkingDirectory=/usr/local/bin
LimitNOFILE=2097152
TasksMax=infinity
ExecStart=/usr/local/bin/simpledns /etc/simpledns/config.json
Restart=on-failure
StartLimitInterval=180
StartLimitBurst=30
RestartSec=5s

[Install]
WantedBy=multi-user.target

6. Port 53 (the DNS server port) is usually in use by default. To solve this, follow https://unix.stackexchange.com/a/676977/405697 then run systemctl restart systemd-resolved
7. Make sure that no other DNS servers (such as bind9) are running
8. Enable the Simple DNS server service on startup & start it now:

systemctl enable --now simpledns.service