What Is Dynamic DNS?

Most home connections have a dynamic public IP that can change at any time. Dynamic DNS solves that:

1. You create a host name with a DDNS provider (or use your own domain with an API-capable DNS host).
2. Your router, NAS or a small client app checks your public IP regularly.
3. When it changes, the client calls the provider's update API, and the provider updates the A (and AAAA) record with a short TTL.

Many routers and NAS systems have DDNS clients built in for popular providers.

Limits

• DDNS only finds your home; you still need port forwarding to reach a device behind NAT.
• It doesn't work behind carrier-grade NAT, because your router doesn't have its own public IPv4 address.

Modern alternatives

Tunnels and mesh VPNs such as Tailscale, ZeroTier and Cloudflare Tunnel connect out from your home, so they work behind CGNAT without port forwarding or DDNS.

• A NAS reachable at nas-home.example.net from anywhere, with DDNS updating the address and port forwarding for 443.
• A home VPN server at vpn.example.com, updated by the router's DDNS client.

To check what a DDNS name currently points to, run dig +short home.example.net and compare it with your public IP (from curl -s https://api.ipify.org). If they differ, the update client isn't working.

LightAtom's connections view shows incoming connections when you reach your home Mac from outside, with the remote address they come from.