81. What is 'containerization' in modern OS?
- a) Lightweight process isolation using namespaces/cgroups
- b) Compressing executable files
- c) Encrypting memory pages
- d) Virtual disk partitioning
Answer: A - Containers (e.g., Docker) share the host OS kernel but isolate processes/resources.
82. Which concept enables 'snapshots' in file systems?
- a) Copy-on-Write (CoW)
- b) Journaling
- c) Inode duplication
- d) Memory-mapped files
Answer: A - CoW preserves original data until modified (used in ZFS/Btrfs).
83. What is 'Byzantine fault tolerance' in distributed systems?
- a) System resilience against arbitrary/node failures
- b) CPU overheating protection
- c) Network packet encryption
- d) Disk redundancy in RAID
Answer: A - Handles scenarios where components may fail or behave maliciously.
84. Which Linux kernel feature isolates container resources?
- a) cgroups
- b) SELinux
- c) iptables
- d) cron
Answer: A - Control groups (cgroups) limit CPU/memory/IO for containers.
85. What is 'Lamport timestamp' used for?
- a) Logical clock for event ordering in distributed systems
- b) Measuring disk latency
- c) Process execution timing
- d) File modification tracking
Answer: A - Determines "happened-before" relationships without synchronized clocks.
86. Which Windows feature provides container isolation?
- a) Windows Containers with Hyper-V isolation
- b) Task Manager
- c) Windows Defender
- d) NTFS permissions
Answer: A - Uses lightweight VMs for stronger security boundaries.
87. What is 'two-phase commit' (2PC) protocol?
- a) Distributed transaction atomicity guarantee
- b) Dual-core CPU synchronization
- c) Memory cache coherency
- d) RAID-1 disk mirroring
Answer: A - Coordinates commit/abort across multiple database nodes.
88. Which command manages Linux containers (LXC)?
- a) lxc-* commands (e.g., lxc-start)
- b) docker
- c) podman
- d) kubectl
Answer: A - LXC provides OS-level virtualization via CLI tools.
89. What is 'Paxos algorithm' used for?
- a) Distributed consensus in unreliable networks
- b) Page replacement
- c) Disk scheduling
- d) Process migration
Answer: A - Ensures agreement among nodes despite failures (basis for Raft).
90. Which filesystem is optimized for containers?
- a) overlayfs
- b) NTFS
- c) ext4
- d) FAT32
Answer: A - OverlayFS merges layers efficiently (used by Docker).
91. What is 'leader election' in distributed systems?
- a) Choosing a coordinator node for consensus
- b) CPU core selection
- c) Process priority assignment
- d) Memory controller activation
Answer: A - Critical for algorithms like Paxos/Raft to avoid split-brain.
92. Which Linux namespace isolates process IDs?
- a) PID namespace
- b) NET namespace
- c) MNT namespace
- d) USER namespace
Answer: A - Allows containers to have their own process numbering.
93. What is 'CAP theorem' in distributed systems?
- a) Tradeoff between Consistency, Availability, Partition tolerance
- b) CPU Architecture Principles
- c) Cryptographic Authentication Protocol
- d) Cache Allocation Policy
Answer: A - States that only two of three CAP properties can be guaranteed simultaneously.
94. Which tool orchestrates container clusters?
- a) Kubernetes
- b) Docker Compose
- c) Ansible
- d) Terraform
Answer: A - Kubernetes automates deployment/scaling of containerized apps.
95. What is 'vector clock' used for?
- a) Partial event ordering in distributed systems
- b) GPU performance measurement
- c) Disk seek time optimization
- d) CPU pipeline scheduling
Answer: A - Tracks causality between events across multiple nodes.
96. Which Windows service manages containers?
- a) Docker Desktop Service
- b) Windows Update
- c) Print Spooler
- d) SQL Server
Answer: A - Docker integrates with Windows via a background service.
97. What is 'sidecar pattern' in containers?
- a) Auxiliary container enhancing main app (e.g., logging)
- b) Dual-container failover
- c) Shared memory between containers
- d) Nested containerization
Answer: A - Extends functionality without modifying the primary container.
98. Which protocol implements distributed locks?
- a) ZooKeeper Atomic Broadcast (ZAB)
- b) HTTP
- c) FTP
- d) SMTP
Answer: A - ZooKeeper provides coordination services for distributed apps.
99. What is 'immutable infrastructure' in DevOps?
- a) Containers/VMs replaced rather than modified
- b) Read-only file systems
- c) Non-upgradable kernels
- d) Hardware with soldered components
Answer: A - Ensures consistency by redeploying from known images.
100. Which Linux command debugs container networking?
- a) nsenter
- b) ping
- c) netstat
- d) curl
Answer: A - nsenter accesses container network namespaces.