Thi Tiếng Anh Chuyên Ngành · Tổng: 100 điểm · 90 phút
Tình huống: Bạn là kỹ sư thông tin của đơn vị, phụ trách phân tích mạng truyền dẫn, khắc phục sự cố mạng dữ liệu và soạn báo cáo kỹ thuật cho chỉ huy.
40 điểm · 40 phút · Đọc 2 văn bản và trả lời các câu hỏi
The Public Switched Telephone Network (PSTN) represents the world's largest and oldest telecommunications infrastructure. Initially designed purely for analogue voice transmission, the PSTN has evolved significantly over decades to support digital signals, data services, and internet connectivity. The network is structured around a hierarchy of switching centres — from local exchanges serving individual subscribers to international gateway exchanges connecting national networks.
The local loop, which is the physical connection between a subscriber's premises and the local exchange, was historically the most significant bottleneck in network performance. Copper wire pairs, while adequate for voice telephony, impose severe limitations on bandwidth. To address this constraint, technologies such as ADSL (Asymmetric Digital Subscriber Line) were developed to increase data transmission rates over existing copper infrastructure without replacing the cables themselves.
Voice over Internet Protocol (VoIP) represents a fundamental transformation in telephone network architecture. Instead of establishing a dedicated circuit between caller and recipient — as traditional telephony requires — VoIP digitises the voice signal, compresses it using codecs, and transmits the resulting data packets over an IP network. This packet-switched approach is dramatically more efficient than circuit-switching because network resources are only occupied when actual data is being transmitted.
The transition to VoIP also introduces new dependencies and vulnerabilities. Because VoIP relies on the same infrastructure as data networks, voice quality is directly affected by network congestion, packet loss, and latency. Quality of Service (QoS) mechanisms are therefore essential in modern networks to prioritise voice traffic and ensure acceptable call quality even under heavy network load.
Xác định mỗi câu sau là TRUE, FALSE hoặc NOT GIVEN theo Văn bản 1.
Chọn đáp án đúng nhất dựa trên Văn bản 1.
Chọn từ thích hợp để điền vào chỗ trống. Mỗi từ chỉ dùng một lần.
Điền thông tin còn thiếu vào bảng dưới đây dựa trên Văn bản 1.
| Công nghệ | Chức năng chính |
|---|---|
| PSTN | |
| ADSL | |
| VoIP | |
| QoS |
A. The OSI Model as a Design Framework
The Open Systems Interconnection (OSI) model provides a conceptual framework for understanding how data travels through a network. Its seven-layer architecture — from the physical layer at the bottom to the application layer at the top — allows engineers to design, troubleshoot, and upgrade individual components of a network without modifying the entire system. Each layer communicates with the layers immediately above and below it through defined interfaces called protocols.
B. Network Topologies and Their Trade-offs
Network topology refers to the arrangement of nodes and connections within a network. Star topology, where all devices connect to a central hub or switch, offers simplified troubleshooting and fault isolation but introduces a single point of failure at the central device. Mesh topology, in contrast, provides multiple paths between nodes, dramatically increasing fault tolerance but at the cost of greater cabling complexity and higher equipment costs.
C. Routing and Switching Fundamentals
Routers operate at the network layer (Layer 3) and make forwarding decisions based on destination IP addresses. They maintain routing tables that list available paths to all known network destinations. Switches, by contrast, operate at the data link layer (Layer 2) and forward frames based on MAC addresses. The distinction between routing and switching is fundamental to understanding how data finds its path through interconnected networks.
D. Network Security Considerations
Modern networks must incorporate security at every layer of the OSI model. Firewalls inspect and filter traffic at the network and transport layers, while application-layer security mechanisms such as HTTPS and TLS protect data content. Intrusion Detection Systems (IDS) monitor network traffic patterns for anomalies that may indicate an attack. In military networks, defence-in-depth strategies apply multiple overlapping security layers to ensure that no single vulnerability can compromise the entire network.
Chọn tiêu đề phù hợp nhất cho mỗi đoạn từ danh sách. Có 2 tiêu đề dư.
Câu hỏi suy luận — câu trả lời không nằm trực tiếp trong văn bản.
Trả lời mỗi câu hỏi bằng 1–2 câu hoàn chỉnh. Dùng ngôn ngữ của bạn.
30 điểm · 25 phút
Chọn từ đúng nhất để điền vào chỗ trống.
Dùng dạng đúng của từ trong ngoặc.
Mỗi câu có một lỗi. Gõ dạng đúng vào ô bên phải.
Dùng từ khóa để viết lại câu. Không thay đổi từ khóa. Dùng 2–5 từ bao gồm từ khóa.
30 điểm · 25 phút · GV chấm theo rubric
📋 Rubric: Task Achievement · Coherence · Vocabulary · Grammar (mỗi tiêu chí 2.5đ)
📋 Rubric: Task Achievement · Coherence · Vocabulary · Grammar (mỗi tiêu chí 2.5đ)
📋 Rubric: Task Achievement · Coherence · Vocabulary · Grammar (mỗi tiêu chí 2.5đ)