Free SVCB Record Lookup & Checker
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Check live SVCB DNS records, TTL values, and trace the full root-to-authoritative resolution path.
SVCB (Service Binding) Records Overview
What is a SVCB record?
An SVCB record (type 64) is a general-purpose service-binding record that advertises how to reach a service, including endpoint and connection parameters. HTTPS records are a web-specific specialization of SVCB.
Why do you need a SVCB record?
SVCB lets any protocol publish connection hints (aliases, ports, ALPN, ECH) in DNS, enabling faster and more secure service discovery.
SVCB record structure
An SVCB record includes a priority, a target hostname, and service parameters. Example: _service.example.com. 3600 IN SVCB 1 svc.example.com. port="8443" alpn="h2"
How to create a SVCB record?
Add an SVCB record at the relevant service name with a priority, target hostname, and service parameters. For websites, most users will use the HTTPS variant instead.
FAQs
SVCB Record Troubleshooting & Common Fixes
AliasMode target resolution failure or circular alias loops
When an SVCB record has a priority of 0 (AliasMode), resolvers treat it like an alias pointing to another target name. If the target domain does not exist, lacks A/AAAA or ServiceMode records, or creates a circular alias loop back to itself, resolution aborts with a lookup failure.
0 AliasMode records point to an active, valid hostname with live address records. Never add service parameters (like port or alpn) to a priority 0 record—parameters are only valid in ServiceMode (priority 1 or higher).
Legacy applications and older resolvers ignoring SVCB parameters
Because SVCB (type 64) is an opportunistic discovery standard defined in RFC 9460, client software that lacks native SVCB support will ignore the record completely and fall back to querying standard A/AAAA and SRV records on default protocol ports.
Intermediate corporate firewalls dropping Type 64 queries
Some legacy corporate firewalls, deep-packet inspection gateways, and outdated local recursive forwarders (such as unpatched dnsmasq or old router firmwares) drop queries for unknown RFC 3597 RR types, resulting in intermittent timeouts for network clients.
1.1.1.1, 8.8.8.8, 9.9.9.9). If internal clients experience timeouts, update the local DNS forwarder or firewall DNS filter to ensure it supports EDNS0 and unknown RR pass-through.
