BBA — Assistant Programmer — Exam: 12.07.2025 (BUET)প্রশ্ন ও সমাধান
- Set by
- BBA
- Post
- Assistant Programmer
- Exam date
- 12 Jul 2025
- Conducted by
- BUET
- Questions
- 6 (0 MCQ, 6 written)
- Exam guide
- Government IT officer posts · সরকারি প্রতিষ্ঠানের আইটি পদ
- Database · ডেটাবেজ 2
- Programming · প্রোগ্রামিং 2
- Networking · নেটওয়ার্কিং 1
- Web Technology · ওয়েব টেকনোলজি 1
What is the port number used by DNS?
Model answer
DNS uses port 53 for both its transport protocols:
- UDP port 53 — used for the vast majority of DNS queries (standard resolution requests/responses), since it is connectionless and fast, avoiding the overhead of a TCP handshake for typically small (< 512 byte) messages.
- TCP port 53 — used when reliability or larger payloads are required:
- Zone transfers (AXFR/IXFR) between a primary and secondary name server, which can be large and must arrive completely and in order.
- Responses larger than 512 bytes (common with DNSSEC-signed records), where UDP's size limitations (before EDNS0 extensions) would truncate the message.
Exam takeaway: DNS = port 53 on both UDP (default, fast queries) and TCP (large responses/zone transfers) — a frequently tested fact alongside HTTP=80/443, SMTP=25, FTP=20/21.
What is recursion?
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What is an API?
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What is SQL?
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Write an SQL query to find duplicate names in the employee table.
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Write a C program that accepts 10 elements in an array and finds the maximum elements from the array.
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Question text is from the public recruitment exam; answers and explanations are written by ARBS Academy. All past papers · Government IT officer posts guide