モニターの種類
HTTP/2 and HTTP/3 monitors
Verify that your site negotiates HTTP/2 and advertises HTTP/3, and what FastPing can and cannot check about HTTP/3 without making HTTP/3 requests.
- API type
http2- You enter
- URL
- Runs at most every
- Plan minimum
- Needs
- None
HTTP/2. FastPing opens a TLS connection offering the protocols h2 and http/1.1 (ALPN), validates the certificate, and requires the server to choose h2. It then sends one GET request over HTTP/2 and checks the status code (any 200 to 399 by default).
HTTP/3, stated precisely. FastPing cannot make HTTP/3 requests: there is no QUIC client in its runtime. What it reports instead is what it can verify:
- HTTP/3 advertised: the response announces
h3in itsAlt-Svcheader, which is how browsers discover HTTP/3. - QUIC answered (only with the "Warn when HTTP/3…" option): the advertised UDP port answered a QUIC version-negotiation packet, so a QUIC endpoint is really listening there.
Neither proves that an HTTP/3 request would succeed end to end, and the page never claims so. Alt-Svc entries that point to another host are reported but not contacted.
| Field | API option | Default | Notes |
|---|---|---|---|
| URL | url | Required | https:// address only, because browsers use HTTP/2 over TLS |
| Expected status codes | expectedStatus | None | Up to 60 characters |
| Timeout (seconds) | timeout | 15 | 2 to 60 |
| Warn if slower than (ms) | maxMs | None | 0 to 60,000 |
| Warn when HTTP/3 is not advertised or its QUIC endpoint does not answer | requireH3 | None | |
| Check interval | interval | Your plan's minimum | From your plan's minimum up to 24 hours |
Expected status codes accept exact codes (200,204), classes (2xx) and ranges (200-299). Only https:// URLs can be checked, because browsers only use HTTP/2 over TLS.
| Message | What it means | What to do |
|---|---|---|
HTTP/2 200 · HTTP/3 advertised · QUIC answered | Up: HTTP/2 works, h3 is advertised and the QUIC endpoint answered. | Nothing. |
HTTP/2 not supported (ALPN: http/1.1) | Down: the server only offered HTTP/1.1. | Enable HTTP/2 in the web server or CDN. |
HTTP/2 503 | Down: the status code is not accepted. | Check the application, or the expected status codes. |
HTTP/3 not advertised (no h3 in Alt-Svc) · HTTP/2 200 | Warning (only when you asked for HTTP/3): no Alt-Svc entry for h3. | Enable HTTP/3 and the Alt-Svc header on your server or CDN. |
HTTP/3 advertised but the QUIC endpoint did not answer on UDP 443 · HTTP/2 200 | Warning: h3 is advertised but nothing answered QUIC on that UDP port. | Open UDP 443 in the firewall, or stop advertising h3. |
The free HTTP/2 & HTTP/3 checker runs the same checks once and lists the protocols and Alt-Svc entries it found.