# Keep your home server reachable with Dynamic DNS

DevFeed: [Keep your home server reachable with Dynamic DNS](<https://devfeed.tech/articles/keep-your-home-server-reachable-with-dynamic-dns-105916.md>)

Original publisher: [Read original article](<https://www.fastmail.com/blog/keep-your-home-server-reachable-with-dynamic-dns/>)

Author: Andrew Davis

Published: 2026-10-29T00:00:01Z

Content type: release

Language: en

Sources: [Fastmail Blog](<https://devfeed.tech/sources/fastmail-blog.md>)

Topics: [Domain Name System (DNS)](<https://devfeed.tech/topics/dns-resolution-process.md>), [Homelab](<https://devfeed.tech/topics/homelab.md>), [API Economy](<https://devfeed.tech/topics/api-economy.md>)

Tags: [advanced](<https://devfeed.tech/tags/advanced.md>), [api](<https://devfeed.tech/tags/api.md>), [clients](<https://devfeed.tech/tags/clients.md>), [dns](<https://devfeed.tech/tags/dns.md>), [domain](<https://devfeed.tech/tags/domain.md>), [dynamic-dns](<https://devfeed.tech/tags/dynamic-dns.md>), [email](<https://devfeed.tech/tags/email.md>), [home-automation](<https://devfeed.tech/tags/home-automation.md>), [home-server](<https://devfeed.tech/tags/home-server.md>), [https](<https://devfeed.tech/tags/https.md>), [ip](<https://devfeed.tech/tags/ip.md>), [mx-records](<https://devfeed.tech/tags/mx-records.md>), [nas](<https://devfeed.tech/tags/nas.md>), [protocol](<https://devfeed.tech/tags/protocol.md>), [routers](<https://devfeed.tech/tags/routers.md>), [security](<https://devfeed.tech/tags/security.md>), [self-host](<https://devfeed.tech/tags/self-host.md>), [technical](<https://devfeed.tech/tags/technical.md>)

## AI overview

Fastmail's Dynamic DNS support keeps a hostname pointed at a changing home IP for domains whose DNS is hosted with Fastmail. Create a Dynamic DNS API token and an opted-in Dynamic DNS record; the token can update only those records, not ordinary A/AAAA, MX, or DKIM records. Clients such as ddclient can use the dyndns2 endpoint with Fastmail login and token over HTTPS; the post also provides a token-only simple API suited to cron, which can use the request's IP or an explicitly supplied IPv4 or IPv6 address. The token is shown only once and stored in plaintext in client configuration, which the post advises restricting to root with mode 600.

## Source excerpt

This post is about a new feature for people who host their domain's DNS with Fastmail, and it's a technical one. You don't need to change anything about your account or your email software, so if running your own services at home isn't your thing, feel free to skip it. Today we're announcing Dynamic DNS support in Fastmail. It speaks dyndns2 at https://api.fastmail.com/dynamicdns/update, and there's a simpler one-line variant for a self-hoster's crontab. The problem with a home IP address Some customers, myself included, self-host some services at their homes. Residential ISPs typically don't provide a static IP address. It might change daily, monthly or just often enough to be a pain. The problem this creates is you set up home.various.domains pointing at your home IP address, but eventually your IP changes and the hostname doesn't point to you. Your NAS is still running and your home automation is still ticking, but now you can't reach them. dyndns2 is a protocol that has solved this problem for 25 years and is supported by many home routers and popular clients such as ddclient. Getting started To get started, create a new API token of the Dynamic DNS type in Settings -> Privacy & Security -> Manage API tokens. Copy the token somewhere safe before you navigate away as it's only shown once. Then go to Settings -> Domains, click Edit next to your domain, then Customise DNS, and add a record of type Dynamic DNS with the name you want to keep up to date. The record starts out empty and is set via the API. The security of the Dynamic DNS type We built this as a new pseudo record type (an internal, non-standard type that resolves to an A or AAAA record), in the same vein as an ANAME record. Its value can only be set through the API, never in the web interface, so creating one is an explicit opt-in. That is what limits a Dynamic DNS token: it can only write to the records you've opted in, and can't touch an A or AAAA record, your MX records or your DKIM keys. Therefore a to