Networking Interview Questions
10 questions
Networking fundamentals for DevOps roles — DNS, load balancing, and connectivity troubleshooting across the layers most infrastructure incidents actually live in.
How would you differentiate a client-side DNS resolution problem from the authoritative or upstream DNS server itself being unreliable?
IntermediateDNS7 min
An application intermittently fails to resolve a hostname — most requests succeed, but a small percentage fail with a DNS error. How would you track this down?
IntermediateDNSLinux8 min
How does NodeLocal DNSCache in Kubernetes actually reduce DNS-related failures, mechanically?
AdvancedKubernetesDNS7 min
Why does DNS primarily use UDP instead of TCP, and what does that choice trade off for reliability?
IntermediateDNS6 min
During every deployment, a handful of in-flight requests get dropped with connection-reset errors right as old servers are terminated. How do you fix this?
IntermediateNetworking6 min
Your load balancer keeps marking healthy backend servers as unhealthy and removing them from rotation, causing capacity to drop and requests to concentrate on fewer servers. How do you diagnose and fix this?
AdvancedNetworking8 min
What's the actual difference between a Layer 4 and a Layer 7 load balancer, and how does that difference affect what routing decisions each can make?
IntermediateNetworking6 min
Small requests to a service work fine, but any request with a larger payload just hangs and eventually times out, with no error on either side. What's the likely cause?
AdvancedNetworking8 min
An application currently relies on sticky sessions (a user's requests always route to the same backend) to work correctly. Why is this considered an anti-pattern, and how would you actually remove the dependency?
IntermediateNetworking7 min
Should TLS terminate at the load balancer, or should encrypted traffic pass all the way through to the backend servers? What's the actual security and operational trade-off?
IntermediateNetworkingSecurity7 min