Happy Eyeballs
Testing: SVCB/HTTPS AliasMode Test

Under Development: This test is currently a work in progress.

This test verifies whether the browser correctly processes HTTPS AliasMode records (priority 0) and initiates a follow-up query for the alias target name (Section 4.2.1).

The test runs two subtests side by side. The first — Direct (control) — connects directly to the alias target host, which has full A, AAAA, and HTTPS records. A successful result here confirms the server infrastructure is reachable. The second — Via AliasMode HTTPS — connects to a domain that carries only an AliasMode HTTPS record (priority 0) pointing to the same target; no A or AAAA records exist on the alias name itself.

If the browser correctly chases the alias, it resolves the target name and connects successfully, shown as Alias Followed. If it ignores the AliasMode record, the DNS lookup returns no addresses and the connection fails (ERR).

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