TechnitiumSoftware/DnsServer · error · DnsServerException

Zone was not found for domain: {key}

Error message

Zone was not found for domain: {key}

What it means

Thrown by AuthZoneTree.GetOrAddSubDomainZone when the requested domain equals the zone apex (zoneName == domain, case-insensitive) but no AuthZoneNode for that domain exists in the tree, so the GetOrAdd value-factory delegate runs and refuses to fabricate an apex node. It signals that the caller asked for the apex zone itself while only a sub-domain zone can be created on demand. The tree intentionally will not auto-create an apex; it must be registered beforehand.

Source

Thrown at DnsServerCore/Dns/Trees/AuthZoneTree.cs:639

                                currentKey = value.Key;
                            }
                        }
                        while (true);
                    }
                }
            }

            return zones;
        }

        public AuthZone GetOrAddSubDomainZone(string zoneName, string domain, Func<SubDomainZone> valueFactory)
        {
            bool isApex = zoneName.Equals(domain, StringComparison.OrdinalIgnoreCase);

            AuthZoneNode authZoneNode = GetOrAdd(domain, delegate (string key)
            {
                if (isApex)
                    throw new DnsServerException("Zone was not found for domain: " + key);

                return new AuthZoneNode(valueFactory(), null);
            });

            if (isApex)
            {
                if (authZoneNode.ApexZone is null)
                    throw new DnsServerException("Zone was not found: " + zoneName);

                return authZoneNode.ApexZone;
            }
            else
            {
                return authZoneNode.GetOrAddParentSideZone(valueFactory);
            }
        }

        public AuthZone GetAuthZone(string zoneName, string domain)

View on GitHub (pinned to d0484b6c1e)

Solutions

1. Ensure the apex zone is created and registered in the tree (via AuthZoneManager.CreateEmptyApexZone / _root.TryAdd) BEFORE calling GetOrAddSubDomainZone for any apex-equal domain.
2. If the apex may legitimately be absent, check with TryGet(zoneName) first and only call GetOrAddSubDomainZone when zoneName != domain.
3. Catch DnsServerException and surface a clearer 'apex zone must be created first' error to the upstream caller.

Example fix

// before
var sub = _root.GetOrAddSubDomainZone(zoneName, zoneName, factory);

// after
if (!_root.TryGet(zoneName, out _))
    throw new DnsServerException("Apex zone must be created before adding sub-domains: " + zoneName);
var sub = _root.GetOrAddSubDomainZone(zoneName, childDomain, factory);

// Ensure apex is registered and domain != zoneName before calling sub-domain ops
bool CanGetOrAddSubDomain(AuthZoneTree root, string zoneName, string domain)
{
    if (zoneName.Equals(domain, StringComparison.OrdinalIgnoreCase))
        return root.TryGet(domain, out var node) && node.ApexZone is not null;
    return root.TryGet(zoneName, out _);
}

try { return root.GetOrAddSubDomainZone(zoneName, domain, factory); }
catch (DnsServerException ex) when (ex.Message.StartsWith("Zone was not found for domain"))
{
    // apex missing — create/retrieve it, then retry or surface upstream
    throw new InvalidOperationException("Apex zone not initialized: " + zoneName, ex);
}

When it happens

Trigger: Calling GetOrAddSubDomainZone(zoneName, domain) with domain equal to zoneName (apex) before the apex zone has been added to the AuthZoneTree via TryAdd/apex registration; the GetOrAdd factory delegate is invoked for the missing domain node and immediately throws because isApex is true.

Common situations: Adding records to a zone whose apex was never created (CreateEmptyApexZone not yet called), misordered zone initialization that creates sub-domains before the apex is registered, or a race where the apex was deleted concurrently with a sub-domain add request.

Related errors

• The domain name '<domain>' does not belong to the zone: <zon
• Zone was not found for domain: <domain>
• Zone was not found: {zoneName}
• DNS zone type not supported.
• Zone already exists: <zoneInfo.DisplayName>

AI-assisted analysis of TechnitiumSoftware/DnsServer@d0484b6c1e (2026-08-13). Data as JSON: /api/errors/ccf3a0f0b30d58d1. Report an issue: GitHub.