What is Anycast and Ultralow?

Our network spans many locations worldwide, striving to have a presence in the main city of most countries or states.

In each location, we always select two different providers with distinct network paths, hosted in separate datacenters.

Most locations are accessible via anycast, while all locations are available through ultralow (unicast with DNS steering).

We provide two anycast IPs assigned to the two different classes of providers present in each location, as described above. They have no preference over one another and are in place to ensure that if one becomes unreachable for any reason, the other will continue to operate. The DNS client will automatically fall back.

Note that if one provider fails in one location, the associated anycast IP will automatically be rerouted to another location. This combination offers high reliability.

With ultralow, the mechanism is similar, but our DNS steering system does all the work. Our *.dns.nextdns.io hostname does always resolve to two IPs across two different providers for a given location, and we also reroute to other locations when a provider's health in a location is degraded.

Ultralow provides access to more locations, potentially offering even lower latency than with anycast. For ultralow to function, you need to connect via our hostnames, which only works with encrypted protocols like DoH (DNS over HTTPS), DoT (DNS over TLS), and DoQ (DNS over QUIC).