A practical guide to connectivity.

DNS resolution

DNS maps hostnames to addresses. A site can fail to load if the DNS record is stale, points to an old server or has not propagated to the resolver in use.

Check that the hostname resolves to the intended IP address. Remember that browsers, operating systems and network resolvers may cache answers for different lengths of time.

TCP connections

Many HTTPS services use TCP port 443. A successful TCP handshake confirms that packets can reach a listening endpoint and return—not that the application protocol or authentication will succeed.

Connection timeouts can be caused by filtering, broken routing, an unavailable service, or a firewall rule. Compare results from more than one independent network before deciding where the fault lies.

HTTPS and TLS

TLS authenticates a server using certificates and establishes encrypted communication. After TCP connects, a TLS handshake negotiates cryptographic parameters and validates the peer certificate.

A TLS timeout is a different symptom from a DNS failure or a refused TCP connection. It helps narrow the investigation but does not identify a single cause on its own.

Understanding latency

HTTP response time includes networking, protocol and server processing. It is not directly equivalent to ICMP ping, TCP handshake time or application latency.

The browser-based check on our Network Tools page samples five requests to a local health endpoint and reports a simple average. Repeat the test at different times and across networks to see variation.

Troubleshooting checklist

1. Verify the hostname and the resolved address.
2. Confirm the intended service is listening on the destination port.
3. Test from both the server and a separate network.
4. Distinguish a TCP timeout, TLS failure and HTTP error status.
5. Check server logs and packet traces before changing configuration.
6. Record the network, time and symptoms so comparisons are meaningful.