CS Fundamentals Quick Revision
Use this sheet the week before interviews. Each line links to the full lesson.
Operating systems
| Question | Short answer | Lesson |
|---|---|---|
| Process vs thread? | A process has its own address space; threads share memory within a process | Processes and threads |
| What is a deadlock? | Processes wait on each other's resources forever (4 Coffman conditions) | Deadlocks |
| Paging vs segmentation? | Fixed-size pages vs logical variable-size segments | Memory management |
| Mutex vs semaphore? | Mutex has an owner; semaphore is a counter for signalling | Synchronization |
| Round Robin? | Pre-emptive scheduling with a time quantum | CPU scheduling |
DBMS
| Question | Short answer | Lesson |
|---|---|---|
| ACID? | Atomicity, Consistency, Isolation, Durability | Transactions |
| 1NF, 2NF, 3NF, BCNF? | Atomic values; no partial deps; no transitive deps; every determinant is a key | Normalization |
| WHERE vs HAVING? | Filter rows before grouping vs filter groups after | Joins and aggregation |
| Clustered index? | Determines physical row order; one per table | Transactions and indexing |
Networks
| Question | Short answer | Lesson |
|---|---|---|
| TCP vs UDP? | Reliable ordered stream vs unreliable datagrams | Transport layer |
| What happens when you type a URL? | DNS, TCP, TLS, HTTP, render | Type a URL |
| HTTP vs HTTPS? | HTTPS adds TLS encryption and authentication | TLS and security |
| Subnet mask /26? | 64 addresses, 62 usable hosts | IP and routing |
OOP and design
| Question | Short answer | Lesson |
|---|---|---|
| Four pillars? | Encapsulation, inheritance, polymorphism, abstraction | Python OOP, Java OOP |
| Overloading vs overriding? | Same name different params vs same signature in subclass | Java OOP |
| CAP theorem? | In a partition choose consistency or availability | Databases and sharding |
| How would you design a URL shortener? | Key generation, key-value store, cache, redirects | Case study |
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