Website Monitoring Best Practices: How to Monitor a Web App Properly
A web application usually needs more than one check. A site can return `200 OK` while still having broken DNS, an expiring certificate, a maintenance page instead of real content, or a problem that only affects part of the user journey. Good monitoring combines multiple signals so you verify not only that the server answered, but that the application is actually working as expected.
How to think about monitoring a web application
A web application is not a single layer. It depends on DNS, network reachability, TLS, HTTP behavior, and often the actual content returned to the browser. If you monitor only one of those layers, you get only a narrow slice of reality.
That is why good monitoring combines several signals. For a public website, that usually means confirming that the domain resolves correctly, that HTTPS returns the expected status, and that the page also contains the content or marker you actually care about.
What you usually want to catch
The domain no longer resolves correctly
A DNS check reveals when the hostname stops resolving or starts pointing somewhere it should not.
The host is reachable, but the web service is not
A basic port check can help separate network-level reachability from a problem higher up in the stack.
HTTPS returns the wrong content
A page can still return 200 while serving the wrong content. That is exactly where content checks help.
The certificate is close to expiry
A website can still appear up today while the TLS certificate is about to become tomorrow’s outage.
A practical monitoring setup for a website
Start with DNS
First confirm that the domain resolves correctly. If it is important to you, also verify that it resolves to the IP you expect.
Use HTTPS checks on the right path
Do not always default to the homepage. A health endpoint or another representative page can be a cleaner signal of application health.
Set the expected status deliberately
The default of `200` is sensible in many cases, but the right status depends on what your endpoint is designed to return.
Validate the content too
If you want confidence that the page is really serving what it should, add a stable marker that must appear in the response.
How to assemble website monitoring in practice
A sensible website monitoring setup often combines several views of the same service:
Domain app.example.com Check 1 DNS resolution Check 2 HTTPS /health -> 200 Check 3 Homepage contains expected marker Check 4 Port 443 is reachable
DNS catches resolution mistakes
If the domain points to the wrong place or stops resolving, you want to know that before the application symptoms mislead you.
Port checks confirm the basic listener
They help separate a reachable port from a problem in TLS or HTTP behavior.
HTTPS health endpoints validate service behavior
A health endpoint is often a cleaner and more stable signal than the homepage alone.
Content checks confirm the real page state
They help detect maintenance pages, error fallbacks, or other false-green responses that still return a technically successful status.
Why status code alone is often not enough
An application can return `200 OK` and still be broken from the user’s point of view. Common examples include maintenance pages, frontend fallback pages, or content that is technically delivered but functionally wrong.
That is why content validation matters so much. It does not just tell you that the server responded. It tells you whether it responded with something meaningful.
Simple website check vs proper website monitoring
| Topic | Simple check | Proper monitoring |
|---|---|---|
| What it verifies | One layer, usually just the HTTP response. | DNS, HTTPS, page content, and other important layers. |
| Risk | Can miss maintenance pages or broken DNS. | Better at separating DNS, TLS, content, and application issues. |
| Troubleshooting value | Lower, because it gives less context. | Higher, because different checks explain different failure modes. |
Want a deeper look at what HTTP and HTTPS checks actually validate?
Our HTTP and HTTPS monitoring guide explains status codes, content checks, and why `200 OK` does not always mean the application is healthy.
Read the HTTP and HTTPS monitoring guide →Typical scenarios
DNS is broken, but the IP still works directly
The web server may still be running, but users cannot reach it through the domain. That is why DNS checks matter.
Port 443 is open, but the certificate is expiring
A basic port check looks healthy, while an HTTPS check correctly catches a TLS-layer problem.
The homepage returns 200, but it is a maintenance page
Status code alone misses the problem, while a content check catches it.
The health endpoint is green, but the homepage is broken
That is why it often makes sense to combine one technical health check with one user-facing content check.
Important limitations
- ● If your frontend, API, and admin area live on different domains or subdomains, they usually deserve separate monitoring.
- ● A poorly chosen content marker can create both false positives and false negatives.
- ● A port check does not prove that the application itself is healthy. It only proves that a listener is reachable.
- ● Ping is not always decisive for public websites, because some hosts block ICMP while the website itself still works normally.
Manual checks people often use
dig app.example.com Useful for verifying that the domain returns the A or AAAA records you expect.
curl -I https://app.example.com/health A fast way to check the status code and a basic endpoint response.
curl -s https://app.example.com/ | grep "Welcome to Example" A manual equivalent of content validation when you want to confirm a specific page marker.
Frequently asked questions
A web application is healthy only when the important layers are healthy too.
nsmon lets you combine DNS checks, HTTPS validation, content checks, and other signals into one monitoring setup that reflects the real behavior of your web application. Create a free account and build monitoring that catches both outages and false-green states.