Question 1

What actually happens when a website goes down?

Accepted Answer

"Down" covers several quite different failures, and the error you see narrows it down considerably — which is worth knowing before assuming the site is at fault.

**DNS failure.** The name cannot be resolved to an address. Symptoms: a browser error naming DNS, or a message that the server address could not be found. Causes include an expired domain, a misconfigured or lapsed DNS record, name servers offline, or a DNSSEC validation failure. **The site itself may be running perfectly** — nothing can find it.

**Routing failure.** The address resolves but packets cannot reach it. Causes include a BGP withdrawal or misconfiguration, or an upstream network problem. Symptoms: connection timeouts, with traceroute stopping partway.

**The server is unreachable.** Resolves and routes fine, but nothing answers — a crashed machine, a firewall rule, or a service not listening. Symptoms: connection refused or timed out.

**The server answers with an error.** This is the most informative case, because the infrastructure clearly works:

**500** — the application itself failed.

**502 Bad Gateway** — a proxy reached the backend and got an invalid response, usually meaning the application is down behind a working front end.

**503 Service Unavailable** — overloaded or deliberately in maintenance.

**504 Gateway Timeout** — the backend took too long.

**429** — you are being rate limited, which is not an outage.

**Certificate problems.** The site is reachable but the browser refuses — an expired certificate being the classic, and entirely self-inflicted, failure.

**Capacity and dependency failures.** The site is up but a database, payment provider, authentication service or CDN it depends on is not — producing partial functionality, which is frequently more confusing for users than a clean outage.

**How to work out whether it is you.** Check the site from a mobile connection rather than your own broadband; use a third-party "is it down" checker, which tests from elsewhere; **flush DNS** and try a different resolver; and check the operator's status page or social account.

**Why one provider's failure takes down many sites.** Concentration in CDNs, DNS providers and cloud regions means a single incident can make large numbers of unrelated sites fail simultaneously.

Question 2

What is BGP, and why does it sometimes break the internet?

Accepted Answer

Border Gateway Protocol is how independent networks tell each other which addresses they can reach. It is the routing system the entire internet depends on — and it works largely on trust, which is

Question 3

What does a DNS server actually do?

Accepted Answer

A DNS server translates names people can remember into the numeric addresses machines actually use to route traffic. Every connection you make begins with a lookup, and if that lookup fails nothing

Question 4

What is an internet shutdown, and how are they actually done?

Accepted Answer

A deliberate disruption of internet access by a government or an actor acting on its instruction, affecting a population, a region or a service. They have become more frequent, and the techniques are

Question 5

Why does my WiFi say connected but there is no internet?

Accepted Answer

The message is telling you something precise and useful: your device successfully joined the local wireless network, but traffic is not reaching the wider internet. That splits the problem cleanly in

Question 6

Why does my internet drop at the same time every day?

Accepted Answer

A regular, predictable drop is a strong clue, because genuinely random faults do not keep a schedule. There are a handful of mechanisms that produce this pattern. Some providers enforce a periodic

Question 7

What is traceroute actually telling you?

Accepted Answer

The path your packets take toward a destination, hop by hop — and it is genuinely useful for diagnosis, provided you know which parts of it to ignore. How it works — a clever trick. Every IP packet

Related Questions