Chartered IT Professional (CITP) Breadth of IT Knowledge and Technical Foundations Flashcards

24 sample cards from the Breadth of IT Knowledge and Technical Foundations deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. In relational data modelling, what is the difference between a primary key and a foreign key?

   A primary key uniquely identifies each row within its own table; a foreign key is a column (or set) in one table that references the primary key of another table, enforcing referential integrity.

2. What conditions must a relation satisfy to be in Third Normal Form (3NF)?

   It must be in 2NF and have no transitive dependencies — every non-key attribute must depend only on the primary key, not on another non-key attribute.

3. What does the term BASE describe, and how does it contrast with ACID?

   BASE = Basically Available, Soft state, Eventual consistency — the consistency model favoured by many NoSQL/distributed stores, trading strict immediate consistency (ACID) for higher availability and partition tolerance.

4. Name the four common categories of NoSQL database.

   Key-value stores, Document stores, Column-family (wide-column) stores, and Graph databases.

5. What is the difference between OLTP and OLAP systems?

   OLTP (Online Transaction Processing) handles many short, write-heavy transactional operations on current data; OLAP (Online Analytical Processing) supports complex, read-heavy analytical queries over large historical/aggregated data for decision support.

6. In data warehousing, what is the difference between a star schema and a snowflake schema?

   A star schema has a central fact table linked to denormalised dimension tables; a snowflake schema normalises those dimensions into multiple related tables, reducing redundancy but adding joins.

7. What does the ETL process stand for, and how does ELT differ?

   ETL = Extract, Transform, Load — data is transformed before loading into the warehouse. ELT loads raw data first then transforms it inside the target system, common with modern cloud data lakes/warehouses.

8. What are the classic 'three Vs' of Big Data, and name two commonly added Vs?

   Volume, Velocity, and Variety; commonly extended with Veracity and Value (sometimes Variability).

9. In the Hadoop ecosystem, what are the roles of HDFS and MapReduce?

   HDFS (Hadoop Distributed File System) provides fault-tolerant distributed storage across commodity nodes; MapReduce is the programming model that processes that data in parallel via a Map phase (filter/transform) and a Reduce phase (aggregate).

10. What distinguishes supervised, unsupervised, and reinforcement learning?

    Supervised learning trains on labelled input-output pairs; unsupervised learning finds structure (e.g. clusters) in unlabelled data; reinforcement learning learns a policy through trial-and-error rewards from interacting with an environment.

11. In machine learning, what is the difference between overfitting and underfitting?

    Overfitting means the model learns noise and fits training data too closely, generalising poorly (low bias, high variance); underfitting means the model is too simple to capture the underlying pattern (high bias, low variance).

12. Define precision and recall for a binary classifier.

    Precision $= \frac{TP}{TP + FP}$ (fraction of predicted positives that are correct); Recall $= \frac{TP}{TP + FN}$ (fraction of actual positives correctly identified).

13. What is the F1 score and why is it used?

    The harmonic mean of precision and recall, $F_{1} = 2 \cdot \frac{P \cdot R}{P + R}$, used to balance the two into a single metric, especially for imbalanced classes.

14. What are the seven layers of the OSI reference model, from layer 1 to layer 7?

    Physical, Data Link, Network, Transport, Session, Presentation, Application.

15. How does the TCP/IP model map to the OSI model in terms of layers?

    TCP/IP has four layers: Link/Network Access (OSI layers 1–2), Internet (OSI layer 3), Transport (OSI layer 4), and Application (OSI layers 5–7).

16. What is the key difference between the TCP and UDP transport protocols?

    TCP is connection-oriented, reliable, ordered and flow/congestion-controlled (with acknowledgements and retransmission); UDP is connectionless, lightweight and best-effort with no guarantee of delivery or ordering.

17. How many bits are in an IPv4 address versus an IPv6 address?

    IPv4 uses 32 bits (about $4.3 \times 10^{9}$ addresses); IPv6 uses 128 bits (about $3.4 \times 10^{38}$ addresses).

18. Given the CIDR notation /26 on an IPv4 network, how many usable host addresses are available?

    A /26 leaves 6 host bits, giving $2^{6} = 64$ total addresses and $2^{6} - 2 = 62$ usable hosts (subtracting network and broadcast addresses).

19. What is the difference between a router and a switch in networking?

    A switch forwards frames within a single LAN using MAC addresses at OSI layer 2; a router forwards packets between different networks using IP addresses at layer 3, making path/routing decisions.

20. Contrast circuit switching with packet switching in wide-area networks.

    Circuit switching reserves a dedicated end-to-end path for the duration of a session (e.g. traditional telephony); packet switching breaks data into independently routed packets that share network links statistically, improving utilisation and resilience.

21. What is MPLS and what advantage does it bring to enterprise WANs?

    Multiprotocol Label Switching forwards traffic using short path labels rather than long network-address lookups, enabling fast, predictable forwarding, traffic engineering, and quality-of-service across a service-provider WAN.

22. What is the role of DNS and DHCP as network services?

    DNS (Domain Name System) resolves human-readable domain names into IP addresses; DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses and network configuration to hosts.

23. In network performance, what is the difference between bandwidth, throughput, and latency?

    Bandwidth is the maximum theoretical data rate of a link; throughput is the actual achieved data rate; latency is the time delay for data to travel from source to destination.

24. What four traffic parameters does Quality of Service (QoS) typically manage to prioritise traffic?

    Bandwidth (allocation), Latency (delay), Jitter (variation in delay), and Packet loss.

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