Dynamic DNS

Automatically update your domain when your IP changes.

Dynamic DNS keeps your domain pointing to your server even when your IP changes.

Overview

If your ISP assigns dynamic IP addresses that change periodically, you need Dynamic DNS (DDNS) to automatically update your domain when your IP changes.

When You Need Dynamic DNS

You need DDNS if:

Your ISP assigns dynamic IP addresses
Your public IP changes periodically
You don't have a static IP from your ISP
You want reliable hosting without paying for static IP

How DDNS Works

1. You register a DDNS hostname (e.g., myhome.ddns.net)
2. An update client runs on your network
3. When your IP changes, the client notifies the DDNS service
4. The DDNS service updates the DNS record automatically

DDNS Providers

DuckDNS:

Free, up to 5 hostnames
Simple setup
Good for personal use

No-IP:

Free tier available
Widely supported by routers
Good documentation

Dynu:

Free tier available
Many features
Good for advanced users

Cloudflare:

Free if you use their DNS
Good integration with other Cloudflare services
Requires Cloudflare account

Setup DDNS

Sign up for DDNS service:

1. Create account with DDNS provider
2. Create a hostname
3. Note your credentials

Configure update client:

Router (if supported):

1. Log into router admin panel
2. Find DDNS settings (usually under Advanced)
3. Select your DDNS provider
4. Enter hostname, username, password
5. Enable DDNS
6. Save and test

Software client:

1. Install DDNS client on server
2. Configure with your credentials
3. Set to run automatically
4. Test IP change detection

Script-based:

1. Create script to check IP
2. Use cron job to run periodically
3. Script calls DDNS update API
4. Logs changes for debugging

Testing DDNS

1. Check current public IP
2. Verify DDNS hostname resolves to that IP
3. Change your IP if possible
4. Verify DDNS hostname updates to new IP
5. Check DDNS service logs

DokuWiki

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