# RedundantDNS nameservers

The RedundantDNS nameservers are DNS servers we run ourselves, in several
regions and at different hosting providers. You attach them to a zone like
any other provider, with no account to open and no credentials to give:
they are one more independent copy of your zone next to the providers you
already use.

## What you get

- **Several nameservers in one attachment.** Each node is a separate
  server with its own name (`vega-latam.redundantdns.org`,
  `altair-na.redundantdns.org`, ...). Attaching "RedundantDNS nameservers"
  to a zone creates the zone on every node, writes every record to each of
  them, and adds every node's name to the zone's NS set.
- **Independent nodes.** The nodes are never a primary and a secondary: the
  platform writes each one directly. A node that is down loses nothing; the
  others keep answering with every record, and the node catches up when it
  is back.
- **Included in your plan.** Every plan includes them, the trial too, with
  no pass-through line on your bill and no per-query charge. They count as
  one provider toward your plan's providers per zone.
- **Free for domains registered or transferred here.** When a zone has the
  name of a domain your organization registered on RedundantDNS or
  transferred in to RedundantDNS, the RedundantDNS
  nameservers are free for it, with or without a plan: the zone does not
  count toward your plan's zones, the nameservers do not count toward its
  providers per zone, and it keeps working after the trial ends or while
  a payment is late (records, reconcile, detach and delete stay open, and
  the nameservers keep receiving your changes). The zone shows a **Free
  with your domain** badge. Other providers and standby attachments follow
  your plan. A zone stops being free when its domain is no longer ours:
  it expired or was deleted at the registrar, or its registration or
  transfer was canceled. The zone and its records are kept and follow
  your plan again; renewing the domain makes the zone free again.
- **Same rules as any provider.** The zone's capabilities, drift checks,
  probes, alerts and the delegation check work as for the other providers.

## Add them

1. On **Providers**, choose **Add connection**, then **RedundantDNS
   nameservers (managed)**. There is nothing to fill in; a name is
   optional.
2. An owner or admin accepts the
   [RedundantDNS Nameservers Terms](/legal/nameservers-terms) once for the
   organization, if it has not already. They are separate from the
   Managed Provider Terms of third-party managed accounts.
3. On the zone's **Providers** tab, choose **Attach provider** and pick the
   connection. The zone is created on every node and the NS plan grows
   with their names.
4. Update the delegation at your registrar with the new NS plan (the
   **Delegation** tab lists it), as for any provider you add.

The provider only appears in the form when the platform has nameserver
nodes; an installation without them does not offer it.

## Reading the status

The attachment shows one line per node: the node's name, its region, its
last sync and its state.

| State | Meaning |
|---|---|
| In sync | every node holds the zone as it is on the platform |
| Partial (the failing nodes named) | some nodes failed their last sync; the others are in sync and keep answering. The platform retries the failing nodes on its own |
| Error | every node failed; the zone keeps being served by your other providers |

A node that stops answering also shows on the zone's **Health** panel and,
when every node of the attachment is down, raises `provider_down` like any
provider. The platform's operators are alerted about a node that is down
and take care of it; you do not need to act.

When the operators retire or add a node, the NS set of the attachment
changes: the zone gets a new serial, every provider receives the new apex
NS set, and the delegation check tells you when the registrar should be
updated.

## Detach

Detaching the RedundantDNS nameservers deletes the zone from every node
(the nodes belong to the platform, so nothing is left behind on them).
Deleting the zone does the same, and so does a billing detach (an unpaid
invoice past the detach period) of a zone that is not free. Remove their
names from the delegation at your registrar first.

## Zone names on the nodes

The nodes serve every organization's zones from one namespace, so a zone
name belongs to one organization with everything under it: you cannot
create a zone inside a verified zone another organization manages
(`_acme-challenge.example.com` next to someone else's `example.com`), nor
above one (`409 zoneNameUnderAnotherOrg`, `409 zoneNameAboveAnotherOrg`).
Subzones of your own zones work as usual. Each zone on a node records your
organization as its owner (the PowerDNS zone account).

If the name (or a parent of it) is already delegated to these nameservers
when you attach them, for example a delegation left at your registrar
after a zone was deleted, the attach asks for proof of control (`409
delegationOwnedElsewhere`): publish the TXT record shown on the zone's
Delegation tab (`_rdns-challenge.<zone>`) on another nameserver your
domain delegates to, then attach again. If your delegation lists only
these nameservers, add one of your own nameservers to it temporarily to
serve that TXT, register or transfer the domain here, or (when your
organization deleted the zone) create it again within 30 days of the
delete. Domains registered or transferred here never need it. See the
API guide, "Zone names, claims and takeover protection".

## Limits

The nodes are sized for these limits each; the platform adds nodes before
any of them passes 60% of a limit.

| Limit | Value | Why |
|---|---|---|
| Zones per node | 20,000 | storage and zone cache stay well below 1 GB |
| Records per zone | 10,000 | matches the platform's provider limits |
| Records per node | 2,000,000 | disk and cache sizing |
| Sustained queries per second, per node | 30,000 | with the packet cache; short bursts around 150,000 |
| Writes | about 50 changes per second per node | the platform batches writes, as for other providers |
| Queries per client | 200 per second per source address, then dropped | amplification and abuse protection |
| Zone size on your plan | unchanged | the nodes are a provider, not a plan |

Fair use applies to queries per plan (Starter lowest, Business highest),
with a warning before any limiting. Enterprise can have dedicated nodes.

## What the platform does

- **Create and manage zones** only: the connection always creates, writes
  and deletes the zone on the nodes (there is no "manage an existing zone"
  or mirror source level, and no credentials to rotate).
- The capabilities are PowerDNS's: every record type of the canonical
  model, TTLs from 1 second, wildcards, an editable apex NS set, no CNAME at
  the apex.