DNS-AID and ARD: agent discovery before the first HTTP request

The gap that well-known files leave

Everything in the protocols dimension so far assumes the agent already knows your domain and fetches a path under /.well-known/. That covers the case where a user says 'check my order at brand.ch'. It does not cover 'find me a Swiss retailer that can quote this in bulk', where the agent has a capability in mind and no domain. Two proposals address the earlier step, from different directions.

DNS-AID: publish your agents in the zone file

DNS for AI Discovery is an IETF Internet-Draft authored at Infoblox, targeted at Standards Track and presented in the DNSOP working group. It reuses the DNS-SD naming style and the Service Binding record type (SVCB, RFC 9460). An agent has its own name, agent-name.example.com, with an SVCB record whose alpn parameter says which protocol it speaks (mcp or a2a, one protocol per record) and where the endpoint is. TLSA records can pin the certificate. For the 'known organisation, unknown agent' case, a well-known name _index._agents.example.com points at an organisation-wide index of all its agents.

; one agent, speaking MCP
orders-agent.brand.ch.        3600 IN SVCB 1 . (
    alpn="mcp"
    port=443
    well-known=mcp.json
)

; the organisation's agent index
_index._agents.brand.ch.      3600 IN SVCB 1 agent-index.brand.ch.

• SVCB is the primary record type. The draft allows TXT records only as a fallback for DNS hosts that cannot publish SVCB yet, and says so is not desirable.
• What the index contains is out of scope. DNS-AID gets the client to the index; the format of the index is left to other specifications.
• It is a draft, revision 02, expiring November 2026. Names, labels and parameters can still change. Publish records if you run agents and want to be early, but expect to update them.

ARD: a search layer for agentic resources

Agentic Resource Discovery comes at the problem from the registry side. Its working group includes participants from Microsoft, Google, Hugging Face and GoDaddy, and the specification is Apache 2.0 licensed. An 'agentic resource' is anything an AI client can call on: an agent, an MCP server, a Skill, an API, a workflow. ARD lets a client ask a discovery service 'what is available for this task?' and get matching entries back. It sits entirely before invocation; the resource is then used through its own protocol. It is explicitly not a runtime and not a single central catalogue: the design expects many discovery services, public and private, each with its own trust and ranking policy.

For a site owner, the relevant piece is the ARD entry that describes your resource, and the manifest that readiness scanners probe at /.well-known/ard.json. Follow the specification on the ARD site for the current entry schema; it is versioned and the fields have moved between revisions.

What Qomvia checks, and what to do now

DNS-AID agent index or ARD is 1 point under Agent protocols. The crawler queries DNS-over-HTTPS for SVCB, HTTPS and TXT records at _index._agents.<domain>, _mcp._agents.<domain>, _a2a._agents.<domain> and agents advertised in the TXT index, then fetches /.well-known/ard.json; a service record with alpn and port or an ARD document passes. If the DNS lookup itself fails the check reports unknown rather than fail.

Honest guidance: if you do not operate any agent or MCP server, skip this until you do. If you operate one, publish the MCP discovery document first, since that is what clients look for today, and add DNS records and an ARD entry as the drafts settle. Both are cheap; neither is where your traffic depends right now.

Questions

Do ChatGPT or Claude query _index._agents today?

Not that either vendor documents. DNS-AID is a working-group draft; today's consumers are readiness scanners and experimental clients. Publish it for the future, not for current traffic.

Is ARD a replacement for MCP?

No. ARD's own site says it is not MCP, A2A, Skills or an API runtime. It only helps a client find a resource; the resource is then invoked through its native protocol.

Can I publish a TXT record instead of SVCB?

The draft permits TXT as a fallback where SVCB is unavailable but calls it undesirable. If your DNS host supports SVCB, use it; Qomvia currently reads the TXT form.