面试题与答案

The OSI model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven abstraction layers.

TCP (Transmission Control Protocol) is connection-oriented, ensuring reliable data delivery. UDP (User Datagram Protocol) is connectionless and provides faster, but less reliable, data transmission.

VLANs logically segment a network into smaller broadcast domains, improving performance and security by isolating traffic.

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.

802.1Q is a standard for VLAN tagging in Ethernet networks, allowing the identification of VLAN membership within Ethernet frames.

The TCP three-way handshake is used to establish a reliable connection between two devices. It involves SYN, SYN-ACK, and ACK messages.

A collision domain is a network segment where collisions can occur, typically in Ethernet networks. A broadcast domain is a logical division of a network, where broadcasts are confined.

DNS translates human-readable domain names into IP addresses, facilitating the routing of data on the Internet.

QoS ensures that network traffic is prioritized based on specific criteria, such as bandwidth, latency, and packet loss, to meet performance requirements.

ACLs control traffic flow by permitting or denying packets based on defined rules. They are commonly used for security and traffic filtering.

NAT overload allows multiple private IP addresses to be mapped to a single public IP address by using different port numbers.

HSRP provides high availability by allowing multiple routers to work together in a group, with one router acting as the active router and the others as standby routers.

A proxy server acts as an intermediary between clients and servers, forwarding requests and responses. It is often used for security and caching.

Network segmentation involves dividing a network into smaller, isolated segments to improve security, performance, and manageability.

Hubs and Spokes topology is a network design where multiple remote sites (spokes) are connected to a central site (hub) for efficient communication.

SNMP is used for managing and monitoring network devices. It allows the retrieval of information and the configuration of network components.

PoE allows the transmission of electrical power along with data on Ethernet cabling, simplifying the deployment of network devices.

802.1X provides port-based network access control, requiring authentication before allowing devices to connect to a LAN.