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Understand DNS, CIDR, ports, load balancing, ingress, and production traffic debugging.
These are the tools you use in this track and what each tool does in production workflows.
OS and Networking
Nginx
Reverse proxy and ingress edge for routing and load balancing.
Which protocol resolves domain names to IP addresses?
DNS maps names to addresses.
What does HTTP status 502 usually indicate?
502 often means proxy got invalid upstream response.
What is a subnet mask used for?
Mask separates network prefix and host bits.
Which port is default for HTTPS?
TLS-secured HTTP typically uses 443.
What does CIDR /24 mean in IPv4?
/24 denotes network prefix length.
What is the role of a load balancer?
Load balancers improve availability and scaling.
What does TTL in DNS affect?
TTL controls DNS cache duration.
What command checks route path to destination?
traceroute reveals hop-by-hop path.
What is NAT commonly used for?
NAT enables outbound internet for private networks.
Which protocol secures web traffic?
TLS provides confidentiality/integrity for HTTPS.
What is an ingress controller in Kubernetes?
Ingress manages L7 routing rules.
What does ping primarily test?
ping uses ICMP echo for connectivity checks.
What is the default port for SSH?
SSH daemon listens on 22 by default.
What is a reverse proxy?
Reverse proxies sit in front of applications.
Why use health checks in networking/load balancing?
Health checks improve reliability and failover.
What does CORS control in browsers?
CORS governs browser cross-origin policy behavior.
What is packet loss?
Loss impacts latency, throughput, and reliability.
What does HTTP 429 indicate?
429 is rate limiting signal.
What is an API gateway used for?
Gateway handles cross-cutting API concerns.
What network layer does TCP operate on?
TCP provides reliable transport services.
Which of the following tools is most commonly used in a DevOps context for defining, provisioning, and managing cloud network infrastructure (e.g., VPCs, subnets, security groups) as code?
Terraform is widely adopted for Infrastructure as Code (IaC) to provision and manage cloud infrastructure, including networking components like Virtual Private Clouds (VPCs), subnets, routing tables, and security groups. While Ansible, Chef, and Puppet are excellent for configuration management, Terraform excels at infrastructure provisioning.
In a Kubernetes environment, what standard defines how container runtimes (like containerd or CRI-O) configure network interfaces for pods, enabling various networking solutions to be plugged in?
CNI (Container Network Interface) is a specification that defines a common interface between network plugins and container runtimes. This allows Kubernetes to support various network solutions (e.g., Calico, Flannel, Cilium) without requiring modifications to the core Kubernetes code.
Integrating network security validation early into the CI/CD pipeline, often through configuration files that define desired network state and policies, is best described by which practice?
Network Policy as Code (NPAC) involves defining network security policies in declarative code that can be version-controlled, tested, and automatically applied within a CI/CD pipeline. This shifts network security left, integrating it earlier in the development lifecycle, aligning with DevSecOps principles. SAST focuses on application code, SIEM on monitoring, and penetration testing is typically a later-stage activity.
What primary networking capability does a Service Mesh (e.g., Istio, Linkerd) provide at the application layer in a microservices architecture?
A Service Mesh provides capabilities like traffic management (routing, load balancing), resilience (retries, circuit breaking), and security (mTLS, access control) for inter-service communication within a microservices application, operating at the application layer without requiring changes to service code.
In a dynamic cloud-native DevOps environment, what is the most common and scalable method for distributing incoming client requests across multiple instances of an application?
Software-defined Load Balancers (both Layer 4 for TCP/UDP and Layer 7 for HTTP/HTTPS) are essential in DevOps for distributing traffic efficiently, enabling scalability, high availability, and seamless deployments in dynamic cloud-native environments. Manual IP tables and long-TTL DNS round-robin are less flexible and scalable for modern microservices.
Which type of data is most crucial for effective real-time network performance monitoring in a highly distributed and ephemeral DevOps environment?
While all options provide valuable insights, network flow data, latency metrics, and packet loss statistics are directly indicative of network performance and health. They are crucial for identifying bottlenecks, intermittent connectivity issues, and unexpected traffic patterns in complex distributed systems managed by DevOps teams.
A microservices application deployed across multiple cloud regions is experiencing intermittent connection issues between services. Which DevOps approach would be most effective for quickly diagnosing and resolving the problem?
In complex distributed systems, manually checking individual servers is inefficient. Distributed tracing combined with correlated network metrics and logs allows DevOps engineers to visualize the entire request flow, identify where latency or errors occur across network hops and service boundaries, and quickly pinpoint the root cause of intermittent connection issues.
In a Kubernetes-native microservices architecture, which component is primarily responsible for providing internal DNS resolution and service discovery for services within the cluster?
CoreDNS is the default DNS server in Kubernetes clusters. It provides service discovery by resolving service names to their respective cluster IPs, allowing pods to communicate with each other using easily resolvable names instead of dynamic IP addresses.
To enforce strict network communication policies between specific namespaces or pods within a Kubernetes cluster, preventing unauthorized traffic, which Kubernetes resource would a DevOps engineer primarily configure?
A Kubernetes NetworkPolicy is a resource that allows you to specify how groups of pods are allowed to communicate with each other and with other network endpoints. It's crucial for implementing a 'least privilege' network security model within the cluster.
How does the adoption of network automation tools (e.g., using APIs, IaC) directly align with core DevOps principles for network operations?
Network automation, by leveraging APIs and IaC, allows network configurations and changes to be managed programmatically. This leads to faster deployment cycles, reduces human error, ensures consistency across environments, and provides an auditable trail of all changes, which are fundamental tenets of DevOps.