IPv6 & Subnets

Dual-stack by default

Every NovaDNS host simultaneously maintains an IPv4 A record and an IPv6 AAAA record. When you call the update endpoint, both addresses are detected from your request and stored independently.

If your network is IPv4-only, the AAAA record is left untouched (or stays empty on first update). If you only have IPv6, the A record is omitted.

IPv6 subnet tracking

Many ISPs assign a dynamic IPv6 prefix — a block like /48 or /64 — to your router, rather than a single static address. Every device on your network derives its own address from that prefix. When the prefix changes (e.g. after a reconnect), all of those addresses change.

Instead of registering each device individually, you can register the prefix itself under a single NovaDNS hostname. Your devices can then construct their own full addresses dynamically using the stored prefix as the base.

How to send a subnet update

Pass the CIDR notation of your prefix as the myip parameter:

$ curl \
  "https://novadns.io/api/update
    ?token=YOUR_TOKEN
    &myip=2001:db8:1234::/48"

{ "ipv4": "203.0.113.42", "ipv6": "2001:db8:1234::/48" }

$ curl \
  "https://email%40example.com:TOKEN@novadns.io/nic/update
    ?hostname=home.novaip.link
    &myip=2001:db8:1234::/48"

good 2001:db8:1234::/48

How prefix tracking works

NovaDNS stores the raw CIDR value in the host's AAAA field. Your device or application reads the prefix back via DNS (or the API), then appends its own interface identifier to construct a full address. This is consistent with how IPv6 stateless address autoconfiguration (SLAAC) and DHCPv6 prefix delegation work in practice.

Limitations