Cloud is not “floating compute.” It is computers on networks with rules. A little networking vocabulary prevents a lot of confusion later.
IP addresses and DNS
- An IP address identifies a host on a network (like a street address).
- DNS maps human names (
example.com) to addresses. When DNS is wrong, everything looks broken even if the server is fine.
Ports and services
A port is not a cable—it is a number that helps the operating system route traffic to the right program. Example: 22 often carries SSH, 443 often carries HTTPS.
When something “does not connect,” beginners learn to ask: right host? right port? firewall? service running?
TCP vs UDP (one sentence each)
- TCP — Reliable delivery (web browsing, SSH, many APIs).
- UDP — Fast, “best effort” (many real-time scenarios). You do not need details on day one—just know they exist.
Why SSH matters for learners
SSH lets you remotely access a Linux shell securely. Most early cloud labs are: create VM → SSH in → run commands.
A tiny troubleshooting mindset
When a connection fails, split the problem:
- Can you resolve the name? (
ping/dig/nslookup—tools vary by OS) - Can you reach the host at all?
- Is the port open and listening?
- Is an application bound correctly (often
0.0.0.0vs127.0.0.1)?
You will not master this in a day. You will recognize these questions in interviews and incidents.
Next step: from your laptop, trace what happens when you open an HTTPS site (conceptually: DNS → TCP 443 → TLS → HTTP).
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