Combined Bank Senior Officer (IT) Exam 25 July 2026 — Question Solution | সমন্বিত ব্যাংক (ব্যাংকার্স সিলেকশন কমিটি) সিনিয়র অফিসার (আইটি) নিয়োগ পরীক্ষা ২০২৬ — প্রশ্ন সমাধান

Correct answer: (a) Real-Time Gross Settlement

RTGS stands for Real-Time Gross Settlement: each high-value payment is settled individually and instantly, and is irrevocable. Bangladesh Bank runs it as BD-RTGS (Bangladesh Real Time Gross Settlement System).
Other options: (b) Rapid Transaction Gross System, (c) Reserve Transfer Gross System and (d) Real-Time General Settlement — none is the name of the system; each garbles the real expansion.

Also know:

• BD-RTGS was formally inaugurated on 29 October 2015.
• BB sets a Tk 1 lakh minimum for customer-to-customer RTGS transfers; government and foreign-currency payments have no minimum.
• BACH = Bangladesh Automated Clearing House; BEFTN = Bangladesh Electronic Fund Transfer Network.

Sources: Bangladesh Payment Systems Report 2025 – Bangladesh Bank; This is how RTGS funds transfer works – UNB; Payment Systems – Bangladesh Bank

Correct answer: (b) 12.50%

Simple interest: I = P × r × t (OpenStax).

1. The sum doubles, so the amount is 2P and the interest is 2P − P = P.
2. P = P × r × 8, so r = 1/8 = 0.125 = 12.5% a year.
3. Check: on 100 Tk at 12.5% the interest is 12.5 × 8 = 100 Tk, giving 200 Tk — doubled.
   Other options: (a) 10% — gives 80% interest in 8 years (100 → 180); doubling at 10% takes 10 years; (c) 15% — gives 120% (100 → 220), more than double; (d) 20% — gives 160%; doubling at 20% takes 5 years.

Also know:

• Shortcut for doubling: rate = 100 ÷ years, and years = 100 ÷ rate.
• To triple, the interest must equal 2P: rate = 200 ÷ years (e.g. 16 years → 12.5%).
• Total repaid T = P + P × r × t (OpenStax).

Sources: 6.3 Simple Interest – OpenStax Contemporary Mathematics

Correct answer: (a) Cache Memory

Cache is a temporary storage area that is more readily available to the processor than the computer's main memory. It is also called CPU memory because it is typically integrated into the CPU chip or placed on a separate chip beside the CPU.
Other options: (b) RAM (Random Access Memory) — main (primary) memory, also close to the CPU, but cache is the more readily available of the two; (c) ROM (Read-Only Memory) — non-volatile, permanent data that can usually only be read, e.g. BIOS start-up programming, not the working memory beside the CPU; (d) Secondary Memory — HDDs and SSDs for long-term storage; slower than primary memory.

Also know:

• Speed order: cache, then RAM (main memory), then secondary storage.
• RAM is volatile: its data is lost when power is turned off.
• DRAM stores each bit in a capacitor and a transistor and must be refreshed frequently; SRAM needs no refresh.
• A program is loaded from secondary storage into primary memory when the OS launches it.

Sources: What is computer memory and what are the different types? – TechTarget

Correct answer: (d) (36.246)_8

1. Hex → binary (4 bits each): 1 = 0001, E = 1110, 5 = 0101, 3 = 0011 → 11110.01010011.
2. Integer part, group 3 bits leftwards from the point: 011 110 → 3 6.
3. Fraction, group 3 bits rightwards, pad a zero: 010 100 110 → 2 4 6.
4. Result: (36.246)_8.
5. Check: 1E.53₁₆ = 30 + 83/256 = 30.32421875; 36.246₈ = 30 + 2/8 + 4/64 + 6/512 = 30.32421875.
   Other options: (a) (36.256)_8 — middle fraction group is 100 = 4, not 5 (its value is 30.33984375); (b) (37.246)_8 — 37₈ = 31, but 1E₁₆ = 30; (c) (35.246)_8 — 35₈ = 29, off by one.

Also know:

• Hex ↔ octal is easiest through binary: 4-bit groups for hex, 3-bit groups for octal.
• Pad with zeros only at the outer ends: left of the integer part, right of the fraction.
• Python's float.fromhex('1E.53') returns 30.32421875, a quick check.

Sources: float.fromhex – Python documentation

Correct answer: (d) Request Routing, Authentication, Rate Limiting, and Load Balancing

An API gateway is a single entry point between clients and back-end services. It acts as a reverse proxy that routes each request to the right service and handles cross-cutting tasks such as authentication, SSL termination and rate limiting; reverse-proxy gateways such as Nginx and HAProxy also load-balance.
Other options: (a) Database Storage and Data Backup — jobs of the database and backup tools, not a request entry point; (b) User Interface Design and Frontend Development — client-side work; the gateway sits behind the client; (c) Source Code Compilation and Debugging — build-time developer tasks, not runtime traffic handling.

Also know:

• Without a gateway, every public-facing service must handle authentication, SSL and client rate limiting itself.
• Gateway patterns: gateway routing, gateway aggregation and gateway offloading.
• Azure API Management does rate limiting and authentication but no load balancing, so it is paired with a load balancer.

Sources: API gateways – Microsoft Azure Architecture Center

Correct answer: (d) DHCP (Dynamic Host Configuration Protocol)

DHCP passes configuration to hosts on a TCP/IP network; built on BOOTP, it adds automatic allocation of reusable network addresses, so a server leases an IP address to each client.
Other options: (a) DNS (Domain Name System) — translates domain names to IP addresses; it does not hand addresses to hosts; (b) FTP (File Transfer Protocol) — transfers files between hosts; (c) HTTP (Hypertext Transfer Protocol) — fetches web resources such as HTML documents.

Also know:

• DHCP has three allocation mechanisms: automatic (permanent), dynamic (for a limited time) and manual (set by the administrator).
• Dynamic allocation is the only one that allows automatic reuse of an address the client no longer needs.
• DHCP uses UDP: server port 67, client port 68.

Sources: RFC 2131: Dynamic Host Configuration Protocol – IETF; DNS – MDN Glossary; RFC 959: File Transfer Protocol – IETF; Overview of HTTP – MDN

Correct answer: (c) Trojan Horse

NIST SP 800-83 defines a Trojan horse as a self-contained, nonreplicating program that appears benign but has a hidden malicious purpose; it often delivers other attacker tools.
Other options: (a) Worm — a self-replicating, self-contained program that spreads without user action; its mark is spreading, not disguise; (b) Spyware — secretly installed to gather information on people or organizations without their knowledge; (d) Adware — software that displays advertisements or promotions, e.g. inserting ads into web pages.

Also know:

• A virus self-replicates by inserting copies of itself into host programs or files; a worm needs no host.
• Trojan horses either replace existing files with malicious versions or add new malicious files.
• In computing, OALD defines a Trojan horse as a program that seems helpful but is designed to destroy data.

Sources: SP 800-83 Rev. 1, Guide to Malware Incident Prevention and Handling – NIST; Spyware – NIST CSRC Glossary; Detect and block potentially unwanted applications – Microsoft Learn; Trojan horse – Oxford Advanced Learner's Dictionary