Dynamic DNS#

The third tab of DNS, at /dns.

An internet provider that changes your address every few weeks makes a fixed name impossible unless something tells the name's DNS provider each time it changes. That is a dynamic DNS client; the router runs one, and this tab configures it.

The services#

Each service is a panel: its name, its provider, and

Field	What it shows
Host names	the names kept up to date
Address from	an interface, or a web lookup and its URL
Zone, user name	when the provider takes them
Password	Set or Not set — never the password
Server	the provider's own unless you named another
Address family	IPv4, IPv6, or both
TTL	when the provider takes one

Last update below the services is the router's own report of each name's last update. Straight after a change it is usually empty: the router checks the address every few minutes and whenever it changes.

Adding and editing a service#

Add dynamic DNS, or Edit on a panel, opens the form:

Field	What it takes
Name	your label for the service: letters, digits, hyphens and underscores
Provider	the DNS provider, by name
Host names	the names to keep pointed at this router
Address to publish	the address of an interface, or the address a web lookup sees
Interface, or Lookup URL	which interface; or which lookup service, and the text before the address in its answer when it says more than the address
Zone	the domain the names are in, for the providers that need it
User name	for the providers that need one
Password or API token	the credential
Server	another server than the provider's own
Address family	IPv4, IPv6, or both where the provider can update both at once
TTL	for the providers that take one
Description

The form knows each provider's rules, and Save stays unavailable, saying why, until they are met: Cloudflare, DigitalOcean, GoDaddy, Hetzner, Gandi and NearlyFreeSpeech.NET need a zone; most providers need a user name, and those that do not (Cloudflare and Duck DNS among them) do not offer the field; only some take a TTL or update both address families.

Delete removes the service after asking.

The two ways to learn the address#

The address of an interface is right when the router's uplink holds the public address itself — a DHCP or PPPoE uplink from the provider.

The address a web lookup sees asks a service on the internet what address your traffic appears to come from. It is right when the router is behind something else that does NAT — a provider's modem in router mode, carrier-grade NAT. Without a URL the client's own default lookup is used.

Publishing an interface's address from behind another NAT publishes a private address, and the name resolves to something nobody can reach.

The password is never shown back#

The router needs the credential to authenticate, so it is kept in its configuration. The page never displays it: the panel says whether one is set, and the form's field starts empty. Left empty, the router keeps the password it has; typing one replaces it. Renaming a service creates it afresh, so a renamed service asks for its password again.

Neither of the reads behind this page carries it for any role, administrators included: it arrives as [redacted], which is how the page knows one is set. The value stays in the configuration, where an administrator's configuration read and the backup still hold it, and a pending change that sets one reads New password in the Commit Bar.

Use a provider token scoped to the one zone it needs, never an account password.

What breaks if you get it wrong#

The wrong interface. Publishing a LAN address, or the address of the uplink that is currently the backup. Pick the interface that holds the public address — the Uplinks table shows which one that is.
Behind carrier-grade NAT with the interface option. Publishes an unreachable address. Use the web lookup.
A token without permission on the zone. The update fails, and the failure is in the router's log, not on this page — see Logs.
Expecting it to be quick. The router checks every few minutes, and the old record then has to expire from caches. A short TTL at the provider is the other half of making a dynamic name useful.