DNS caching in Amazon Linux 2023

Setting Up DNS Caching on Amazon Linux 2023 with dnsmasq

On Amazon Linux 2023, the default DNS handling has moved to systemd-resolved, and the stub listener is disabled by default. To enable local DNS caching efficiently, follow these steps:

1. Use dnsmasq:

   • Install dnsmasq:

     sudo yum install dnsmasq

   • Configure dnsmasq to act as a caching server. Add this to /etc/dnsmasq.conf:

     cache-size=1000
     listen-address=127.0.0.1

   • Start and enable the service:

     sudo systemctl enable dnsmasq
     sudo systemctl start dnsmasq

2. Point /etc/resolv.conf to dnsmasq:

   • Edit /etc/resolv.conf to use the local DNS cache:

     nameserver 127.0.0.1

3. Ensure persistence: To prevent changes to /etc/resolv.conf from being overwritten by network configuration:

   • Use the resolvconf tool or create a static file:

     sudo chattr +i /etc/resolv.conf

Alternatively, you can stick to systemd-resolved and manually enable the DNS stub listener. However, given Amazon Linux's configuration, dnsmasq offers a simpler and more predictable setup.

Let me know if you'd like further clarification!

Cheers, Aaron 😊

I've posted steps on how to do this in the following post: https://repost.aws/questions/QU5b2tZh7cSxmuKlKqHWq5YA/how-do-i-a-setup-a-local-dns-caching-service-on-amazon-linux-2023