CSLB General Building (B) Trade Practice Test
Câu hỏi thường gặp
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Câu hỏi luyện tập mẫu
Một vài câu hỏi thực tế từ ngân hàng miễn phí này, kèm giải thích đầy đủ. Dùng công cụ luyện tập ở trên cho toàn bộ.
- 1. Networking Concepts
Which layer of the OSI model is responsible for logical addressing and determining the best path for packets across an internetwork?
- a.Layer 2 (Data Link)
- b.Layer 1 (Physical)
- c.Layer 3 (Network)
- d.Layer 4 (Transport)
Đáp án: c
Giải thích: Layer 3, the Network layer, handles logical addressing such as IP and makes routing decisions to move packets between networks. The Data Link layer uses physical MAC addresses for local delivery, while the Transport layer manages end-to-end segmentation. Routers operate primarily at Layer 3.
- 2. Networking Concepts
Which protocol resolves an IPv4 address to a MAC address on a local Ethernet segment?
- a.DNS
- b.ICMP
- c.ARP
- d.NTP
Đáp án: c
Giải thích: ARP (Address Resolution Protocol) maps a known IPv4 address to the MAC address needed for Layer 2 delivery. DNS resolves names to IPs, ICMP handles diagnostics, and NTP synchronizes time. ARP operates only within a local broadcast domain.
- 3. Networking Concepts
Which protocol uses TCP port 22 to provide encrypted remote command-line access?
- a.Telnet
- b.FTP
- c.RDP
- d.SSH
Đáp án: d
Giải thích: SSH uses TCP port 22 to provide an encrypted remote shell, replacing insecure protocols like Telnet. Telnet on port 23 sends data in clear text. SSH is the standard for secure device management.
- 4. Network Implementation
A technician needs to connect two buildings 800 meters apart with high bandwidth and immunity to electromagnetic interference. Which medium is best?
- a.Cat 6 UTP
- b.Coaxial cable
- c.Cat 5e UTP
- d.Single-mode fiber
Đáp án: d
Giải thích: Single-mode fiber supports long distances well beyond copper's 100-meter limit and is immune to electromagnetic interference. Twisted-pair copper cannot reach 800 meters. Fiber is the standard choice for building-to-building backbone links.
- 5. Network Implementation
An engineer configures a switch port that should immediately transition to forwarding for a single end host. Which STP feature is appropriate?
- a.Root guard
- b.BPDU flooding
- c.PortFast
- d.Trunk negotiation
Đáp án: c
Giải thích: PortFast lets an access port skip the listening and learning states and move directly to forwarding, which is safe for ports connected to a single end device. It should not be enabled on ports connected to other switches. BPDU guard is often paired with it for protection.
- 6. Network Operations
An operations team uses a port on a switch to capture all traffic passing through other ports for analysis. What is this feature called?
- a.Link aggregation
- b.Port mirroring (SPAN)
- c.Port security
- d.Trunking
Đáp án: b
Giải thích: Port mirroring, also called SPAN, copies traffic from one or more ports to a monitoring port where a packet analyzer or IDS can inspect it. This provides visibility without inline placement. It is a common tool for troubleshooting and security monitoring.
- 7. Network Security
Which access control method assigns permissions to users based on their job function within an organization?
- a.Discretionary access control
- b.Mandatory access control
- c.Role-based access control
- d.Rule-based access control
Đáp án: c
Giải thích: Role-based access control (RBAC) grants permissions according to a user's role or job function, simplifying administration at scale. Users inherit access by being placed into roles rather than being assigned rights individually. This supports least-privilege principles.
- 8. Network Security
Which authentication factor category does a hardware token or smartphone authenticator app represent?
- a.Something you are
- b.Something you know
- c.Somewhere you are
- d.Something you have
Đáp án: d
Giải thích: A hardware token or authenticator app is a 'something you have' factor, since it is a physical or possessed item. Passwords are 'something you know' and biometrics are 'something you are.' Combining factor categories creates multifactor authentication.
- 9. Network Troubleshooting
A fiber link shows very high signal loss and intermittent connectivity. Which physical issue is a likely cause?
- a.A dirty or damaged fiber connector
- b.An incorrect VLAN assignment
- c.A missing default gateway
- d.A DHCP scope exhaustion
Đáp án: a
Giải thích: Dirty, scratched, or damaged fiber connectors cause high signal attenuation and intermittent link problems. Cleaning connectors and inspecting for damage is a standard first check. Optical power meters help quantify the loss.
- 10. Network Troubleshooting
Intermittent connectivity affects devices only during business hours, correlating with heavy equipment operation nearby. Which cabling issue is the likely culprit?
- a.Incorrect DNS server
- b.Electromagnetic interference (EMI) on copper cabling
- c.Exhausted DHCP scope
- d.A duplicate default gateway
Đáp án: b
Giải thích: Interference from nearby heavy equipment induces EMI on unshielded copper cabling, causing errors and intermittent connectivity that tracks with equipment use. Rerouting cable away from the source or using shielded cable or fiber resolves it. The time-based correlation is a strong clue.