Networking Fundamentals for Cloud Engineers
Learn CIDR, DNS and Route 53, TCP, TLS, load balancers, NAT, and security groups, then debug AWS connectivity with a six-step chain.
What You'll Learn
Understanding Why Cloud Networking Breaks
At 11 PM, a food-delivery team in Bengaluru deployed a new payment service.
Planning IP Addresses with CIDR
You are asked whether a new VPC should be 10.0.0.0/16 or 10.0.0.0/24. The wrong answer cannot be fixed later without rebuilding.
Resolving Names with DNS and Route 53
Your application calls api.acme-shop.test. Between that call and a TCP connection, a name must become an IP address.
Understanding TCP and Reading Connection Errors
Two engineers see "can't connect" on the same service. One finds a stopped process in two minutes, and the other spends an hour on firewall rules.
Securing Traffic with TLS and ACM
A payments API works perfectly until 02:00 on the day its certificate expires.
Understanding HTTP and Load Balancer Layers
Every API call your application makes is an HTTP request.
Skills You'll Master
Curriculum Index10 topics
Understanding Why Cloud Networking Breaks
At 11 PM, a food-delivery team in Bengaluru deployed a new payment service.
Planning IP Addresses with CIDR
You are asked whether a new VPC should be 10.0.0.0/16 or 10.0.0.0/24.
Resolving Names with DNS and Route 53
Your application calls api.acme-shop.test. Between that call and a TCP connection, a name must become an IP address.
Understanding TCP and Reading Connection Errors
Two engineers see "can't connect" on the same service.
Securing Traffic with TLS and ACM
A payments API works perfectly until 02:00 on the day its certificate expires.
Understanding HTTP and Load Balancer Layers
Every API call your application makes is an HTTP request.
Understanding Routing, NAT, and Firewalls
Packets do not find their own way. A route table tells each subnet where to send traffic, and firewalls decide whether...
Debugging Connectivity with the Six-Step Chain
Random checking wastes time, because you may fix a symptom of the wrong layer.
Hands-on Lab: Break and Fix a Connection
This lab teaches you to recognize each failure by its symptom. It needs no AWS resources, so it costs nothing.
Quick Reference and Common Mistakes
Quick reference Common mistakes Starting with a VPC that is too small.
Career Impact
Roles that use the skills in this module.
Cloud Engineer
DevOps Engineer
Solutions Architect
Next Modules
Related Guides
Practice on the Coding Sheet
Not a software engineer sheet. Every problem comes from real DevOps, SRE, Platform and Cloud interviews, from your first script to a system you build yourself.
Open the Coding SheetFrequently Asked Questions
Connection refused means the packet reached the server and was actively rejected, usually because nothing is listening on that port. A timeout means no reply came back, which usually points to a firewall, a missing route, or a dead host.
AWS reserves 5 addresses in every subnet. A /24 has 256 addresses, so 251 are usable. A /28 has 16, so 11 are usable.
Neither is better; they work at different levels. Security groups are stateful and attach to resources, and they are enough for most designs. Network ACLs are stateless and attach to subnets, so use them for coarse subnet-wide rules.
502 means the backend sent an invalid response or closed the connection. 503 means there are no healthy targets. 504 means the backend did not answer in time.
It depends on your security and compliance needs. Public traffic must use TLS, and many teams also encrypt internal traffic. Decide per service rather than assuming private means safe.