SPCBL Assistant Manager Exam 6 November 2026 — Question Solution | সিকিউরিটি প্রিন্টিং কর্পোরেশন (এসপিসিবিএল) সহকারী ব্যবস্থাপক নিয়োগ পরীক্ষা ২০২৬ — প্রশ্ন সমাধান

Correct answer: (c) ALU

The ALU (Arithmetic Logic Unit) is the part of the CPU that carries out arithmetic operations (add, subtract) and logic operations (AND, OR, NOT, comparisons). Its result goes to a register.
Other options: (a) Control Unit — it decodes instructions and directs the other parts of the CPU, but does not calculate; (b) Cache — a small, fast memory that keeps recently used data close to the CPU; it stores, it does not compute; (d) Register — a tiny storage location inside the CPU that holds the ALU's operands and results.

Also know:

• The CPU's three main parts: ALU, Control Unit (CU) and registers.
• An accumulator is the register that holds the ALU's running result in simple CPUs.
• Comparisons such as A > B are done by the ALU too; it sets status flags (zero, carry, sign) that the CU uses for branching.

Sources: What is an arithmetic logic unit (ALU) and how does it work? – TechTarget

Correct answer: (a) SaaS

In Software as a Service the user simply uses the provider's application over the internet. NIST's definition gives web-based email as its example: the application is reached through a web browser, and the user does not manage the servers, storage or operating system behind it. Gmail is exactly this.
Other options: (b) PaaS — the user deploys their own applications on the provider's platform (languages, libraries, tools), e.g. Google App Engine; (c) IaaS — the user rents processing, storage and networks and runs their own operating systems and software, e.g. Amazon EC2; (d) NaaS — Network as a Service, renting network functions; it is not one of NIST's three service models.

Also know:

• NIST SP 800-145 names three service models (SaaS, PaaS, IaaS) and four deployment models (private, community, public, hybrid).
• Control grows from SaaS to IaaS: SaaS users control almost nothing, IaaS users control the OS, storage and applications.
• More SaaS examples: Google Docs, Microsoft 365, Dropbox, Zoom.

Sources: The NIST Definition of Cloud Computing (SP 800-145) – NIST

Correct answer: (a) 32

RFC 791, the IPv4 standard, says addresses are a fixed length of four octets (32 bits). They are written as four decimal numbers of 8 bits each, e.g. 192.168.1.1.
Other options: (b) 48 — the length of a MAC (Ethernet hardware) address; (c) 64 — the size of the interface identifier in a typical IPv6 address, not a whole address; (d) 128 — the length of an IPv6 address.

Also know:

• Working: 4 octets × 8 bits = 32 bits, so IPv4 has 2^32 ≈ 4.3 billion addresses.
• Each octet ranges 0–255 (2^8 = 256 values).
• IPv6 (RFC 8200) uses 128-bit addresses written in hexadecimal groups, e.g. 2001:db8::1.

Sources: RFC 791: Internet Protocol – IETF