What ping monitoring actually checks
A ping check sends an ICMP echo request to a host and waits for a reply. That confirms the machine is powered on, connected to the network, and responding at the network layer. That's genuinely useful information — a server that doesn't answer ping at all is very likely completely offline — but it says nothing about anything running on top of the network layer.
A server can answer ping perfectly while its web server process has crashed, its database connection pool is exhausted, or its disk is full and every request is failing with a 500 error. ICMP doesn't know or care about any of that — it operates entirely below the level where a website actually lives.
What uptime (HTTP) monitoring actually checks
An HTTP-based uptime check makes an actual web request — the same kind of request a browser makes — and inspects the real response: the status code, how long it took, and optionally whether specific content appears in the body. This operates at the application layer, where the things that actually break a website for visitors happen.
This catches an entire category of failure ping monitoring is structurally incapable of seeing: a server that's fully reachable on the network but returning errors, timing out on slow database queries, or serving a broken page, a maintenance screen, or someone else's content because of a misconfigured reverse proxy.
A concrete example
Picture a web server whose disk has filled up. The operating system is fine, the network stack is fine, and ICMP replies go out normally — ping monitoring reports the server as healthy the entire time. Meanwhile the application can't write session data or log files, so every real request to the site returns a 500 error. Anyone actually trying to use the site sees it as completely down. Only an HTTP-based check, one that actually looks at the response, would have caught this.
When ping monitoring is still the right tool
Ping isn't obsolete — it's the right, lightweight first check for infrastructure that doesn't speak HTTP at all: a database server, a VPN endpoint, a piece of network hardware. For anything actually serving a website or API, though, ping monitoring alone gives a false sense of security, because it can only ever tell you the network layer is fine — never whether the site itself is.
The two aren't mutually exclusive. A common, reasonable setup runs a fast ping check for quick network-level failure detection, alongside a proper HTTP check that verifies the actual website is serving correct responses — since either one alone leaves a real blind spot the other one covers.