CCNA 面试题与答案
问题 21. Explain the concept of VLAN (Virtual Local Area Network).
VLANs logically segment a network into smaller broadcast domains, improving performance and security by isolating traffic.
问题 22. What is the role of a router in a network?
A router connects different networks and directs data between them based on IP addresses. It operates at the network layer (Layer 3) of the OSI model.
问题 23. What is the difference between a hub, switch, and router?
A hub operates at the physical layer, a switch at the data link layer, and a router at the network layer. Routers connect networks, switches forward data within a network, and hubs broadcast data to all connected devices.
问题 24. What is NAT (Network Address Translation) and why is it used?
NAT allows multiple devices on a local network to share a single public IP address, providing security and conserving IP addresses.
问题 25. Explain the purpose of ICMP (Internet Control Message Protocol).
ICMP is used to send error messages and operational information about network conditions. It is commonly used for troubleshooting.
用户评价最有帮助的内容：
- What is the purpose of ARP (Address Resolution Protocol)?
- Explain the purpose of the DHCP (Dynamic Host Configuration Protocol).
- What is the role of a router in a network?
- What is the purpose of the subnet mask in networking?
- What is the difference between static routing and dynamic routing?