What Is Dynamic DNS And How Can It Help Me?

by Billy J Long Guidance, PSA Articles

Article (PSA‑0014)

Why a Changing IP Address Can Be a Problem

When you run a server from home (web site, game server, CCTV, VPN, etc.) you need a way for people on the Internet to find *your* device. Most residential ISPs assign a **dynamic public IPv4 address** that can change every few hours, days, or weeks. If the address changes, anyone using the old address will lose connectivity.

Dynamic vs. Static IP Addresses

  • Dynamic IP – Assigned by the ISP’s DHCP server. It may change at any time (often nightly or after a router reboot). No extra charge, but the address is not reliable for a public service.
  • Static IP – Fixed for the life of the contract. Usually only offered on business‑class plans and often costs extra (sometimes $5–$20 per month). It gives you a stable address without extra software.

Quick DNS Refresher

DNS (Domain Name System) translates human‑readable names (example.com) into the numeric IP addresses computers actually use. Think of it as an online phone book: you look up a name, get a number, and the call (or web request) is placed.

The Core Issue: Your Dynamic IP + DNS

Traditional DNS points a domain name to a single static IP. If your public IP keeps changing, the DNS record quickly becomes outdated, and anyone trying to reach your service sees a dead address.

Dynamic DNS (DDNS) – The Solution

Dynamic DNS services automatically keep a DNS record in sync with your current public IP.

  • You sign up for a DDNS provider (e.g., No‑IP, DuckDNS, Cloudflare API‑based updates, or the legacy Dyn service).
  • The provider gives you a sub‑domain such as myhome.no‑ip.org or myserver.duckdns.org.
  • A client (built‑in to most modern routers, or a small program on a PC/Raspberry Pi) monitors your public IP. Whenever the IP changes, the client sends an update to the DDNS provider via a secure API (HTTPS or DNS‑UPDATE RFC 2136).
  • The provider instantly updates the DNS record, so the domain name always points at your current IP.

Where to Run the DDNS Client

  • Router – Most consumer routers (e.g., ASUS, Netgear, TP‑Link, Linksys) have a “Dynamic DNS” or “DDNS” section where you can enter your provider’s hostname, username, and password.
  • Dedicated device – If the router doesn’t support DDNS, install a client on a computer, Raspberry Pi, or NAS (most Synology/QNAP devices include DDNS support).
  • Cloud‑based updates – Some providers (Cloudflare, Google Domains) let you use a simple script or curl command to update the record from anywhere on the Internet.

Security & Best‑Practice Tips

  • Use a **strong, unique password** for the DDNS account – the update client sends these credentials on every change.
  • Prefer providers that support **TLS/HTTPS** for updates (No‑IP, DuckDNS, Cloudflare).
  • Keep your router’s firmware up to date; many updates fix DDNS‑related vulnerabilities.
  • If you only need occasional remote access, consider a **VPN** or a cloud reverse‑proxy (e.g., Cloudflare Tunnel) which provides a stable endpoint without exposing your home IP.

Step‑by‑Step: Setting Up DDNS (Example with No‑IP)

  1. Create a free No‑IP account and choose a host name (e.g., myhome.no‑ip.org).
  2. Log into your router’s admin console → Dynamic DNS (or DDNS) section.
  3. Select “No‑IP” from the provider list, then enter the host name, your No‑IP username, and password.
  4. Save the settings. The router will now test the connection and report the current IP.
  5. Confirm by visiting myhome.no‑ip.org from a device outside your network – it should resolve to your public IP.
  6. Whenever your ISP changes the IP, the router automatically updates the record – no further action required.

Alternative Approaches (When DDNS Isn’t Enough)

  • Purchase a static IP from your ISP – the most reliable method for business‑critical services.
  • Use a cloud‑based reverse proxy (e.g., Cloudflare Tunnel, ngrok) – the tunnel endpoint stays constant even though your home IP changes.
  • Hybrid VPN + DDNS – run a site‑to‑site VPN that uses the DDNS name to reach your home network securely.

Bottom Line

Dynamic DNS lets you keep a stable, easy‑to‑remember address for any service you run from a home connection that receives a dynamic IP. It’s a cheap (often free) alternative to paying for a static IP and works with the vast majority of modern routers.

Need Help Getting Started?

If you’d like assistance setting up Dynamic DNS, configuring your router, or exploring alternatives, call PSA Computer Services at (707) 506‑6802. We’ll get you online and reachable—no matter how often your IP changes.