Cubis Engineers

Networking for Cloud Engineers

Understand how traffic moves from a client to a cloud application and back.

Cloud & infrastructureFoundationUpdated Aug 13, 2026networkingclouddnsroutingtroubleshooting

Networking becomes easier when you treat a request as a sequence of decisions. A name resolves to an address, the client selects a route, firewalls allow or deny traffic, a process accepts a port, and an application returns a response.

Terminal
client
  └─ DNS → public address
       └─ route → firewall → load balancer
                              └─ service port → application
                                                   └─ response

Learning path

1 · FoundationAddressing and routingRead interface addresses, prefixes, gateways, cloud subnets, and route decisions.2 · IntermediateDNS, HTTP, and TLSFollow a hostname through resolution, connection, certificate validation, and HTTP.3 · IntermediateCloudflareOperate proxied DNS, edge security, DDoS controls, and private application access.4 · IntermediateNetwork troubleshootingLocate the failing layer with evidence instead of changing several systems at once.

Working vocabulary

TermPractical meaning
AddressIdentifies an interface on an IP network
PrefixDefines which addresses belong to a network, such as /24 or /64
RouteTells the host where to send traffic for a destination
SocketA protocol, local address, and port used by a process
FirewallApplies allow or deny policy to traffic
NATRewrites addresses, commonly at an IPv4 network boundary
Load balancerAccepts client traffic and selects a healthy backend

Read a Linux host without changing it

Terminal
ip -brief link
ip -brief address
ip route
ip -6 route
resolvectl status
ss -lntup

These commands answer six useful questions: which interfaces are up, which addresses they own, where IPv4 and IPv6 traffic goes, which DNS resolver is active, and which processes are listening.

Describe the failure precisely Record the source, destination, protocol, port, expected result, actual result, and timestamp. “The API is down” is vague. “Host A times out connecting to api.example.com:443, while DNS returns the expected address” identifies the next layer to inspect.

Safety boundaries

  • Keep the cloud provider console available before changing an interface, route, firewall, or SSH path.
  • Capture the current configuration and prepare the exact rollback command first.
  • Change one layer at a time, then repeat the same test.
  • Treat packet captures as sensitive; they can contain internal addresses, hostnames, tokens, and unencrypted payloads.

References

Linux command reference

A compact operational reference for daily server work and first-response troubleshooting.

Addressing and Routing

Read IP prefixes, cloud subnets, gateways, and the routes a Linux host will use.

On this page

Learning pathWorking vocabularyRead a Linux host without changing itSafety boundariesReferences