FAQ
Frequently asked questions about our services
What is Dynamic DNS?
Dynamic DNS maps a fixed hostname (like yourname.mydns.se) to your changing home IP address. A small scheduled task on your end calls our update URL whenever your IP changes, and we update the DNS record automatically.
How does the DynDNS protocol work?
The Dynamic DNS protocol is a simple HTTP-based mechanism: your client sends a request with your hostname and credentials, the server verifies them and updates the DNS record to point to your current IP. MyDNS uses a simplified version where your IP is detected automatically from the connection — you just call a URL with
curl and we handle the rest. See our info page for a full technical breakdown of the protocol.Does MyDNS work with my router's built-in DynDNS client?
Yes! We support the standard DynDNS2 protocol at /nic/update. In your router's Dynamic DNS settings, choose "Custom" and configure:
- Server: mydns.se
- Path: /nic/update
- Username: yourhost.mydns.se
- Password: your password
This works with ASUS, Netgear, TP-Link, OpenWrt, DD-WRT, pfSense, and most other routers. See the info page for ddclient and inadyn examples.
Is it really free?
Yes, completely. We've been running this service free of charge since 2003. There are no premium tiers, no ads, and no hidden limits.
I updated my address but it still points to the wrong IP?
DNS changes can take up to 5 minutes to propagate. If it still hasn't updated after that, make sure you're calling the correct URL and that the response says "Updated". Also check that your local DNS cache isn't stale — try
nslookup yourhost.mydns.se to see the current record.How long can I keep my hostname?
As long as you want. The only requirement is that you update at least once a month so we know the hostname is still in use. Inactive hostnames may be recycled after a long period of inactivity.
What happens if I forget to update?
Your hostname will continue to point to the last known IP. If it stays inactive for an extended period, it may eventually be deactivated. Simply log in and trigger an update to reactivate it.
How do I update my hostname automatically?
Linux / macOS: Add a cron job. Open crontab -e and add:
14 21 * * * curl -s "https://mydns.se/u.php?h=yourhost.mydns.se&p=password"
Windows: Use Task Scheduler or the command line:
schtasks /create /sc daily /tn "mydns-update" /tr "curl.exe https://mydns.se/u.php?h=yourhost.mydns.se&p=password"
Download curl from curl.se/windows if it's not already installed. Windows 10 and later ship with curl built in.
Router: Many routers (OpenWrt, DD-WRT, pfSense, ASUS, etc.) have a built-in Dynamic DNS client. Set the service to "custom" and point it at your update URL.
Can I use my own domain with MyDNS?
Yes. You can point your own domain's CNAME record at your mydns hostname, or use our SMTP forwarding with a custom domain's MX record.
I set up an MX record but email isn't arriving?
Many ISPs block port 25, which is required for incoming email. Log in and enable our SMTP port forwarding — we'll accept mail on port 25 and forward it to your server on a port of your choice that isn't blocked.
Do you support IPv6?
Currently we only support IPv4 (A records). IPv6 (AAAA records) is not available at this time.
Is the update URL secure?
Yes, you should always use the HTTPS version of the update URL so your password is encrypted in transit. Your password is stored as a bcrypt hash on our servers — we never store it in plain text.
I lost my password. How do I reset it?
Go to the password reset page, enter the email address you registered with, and we'll send you a reset link. The link is valid for one hour.
Can I change my hostname after registration?
Yes. Log in to your settings page and change the hostname field, as long as the new name isn't already taken.
How can I contact you?
Send us an email at hostmaster@mydns.se. We'll do our best to get back to you quickly.