面试题与答案

ARP is used to map a 32-bit IP address to a MAC address on a local network, allowing communication between devices.

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.

ICMP is used to send error messages and operational information about network conditions. It is commonly used for troubleshooting.

DHCP dynamically assigns IP addresses to devices on a network, simplifying network configuration and management.

The subnet mask defines the network and host portions of an IP address. It is used in conjunction with IP addresses for routing and addressing purposes.

Static routing requires manual configuration of routes, while dynamic routing protocols automatically adapt to changes in the network topology.

Half-duplex communication allows data transmission in both directions, but not simultaneously. Full-duplex communication allows simultaneous two-way data transmission.

ICMP Echo Request and Echo Reply messages are used for ping tests to check network connectivity and measure round-trip time.

A firewall monitors and controls incoming and outgoing network traffic based on predetermined security rules, preventing unauthorized access.

NTP is used to synchronize the clocks of devices on a network, ensuring accurate timekeeping for various applications and services.

The MAC address is a unique identifier assigned to a network interface card (NIC) to enable communication within a network segment.

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.

Subnetting is the process of dividing a network into sub-networks to improve performance and security. It helps manage IP addresses more efficiently.

NAT allows multiple devices on a local network to share a single public IP address, providing security and conserving IP addresses.

STP prevents loops in Ethernet networks by blocking redundant paths. It ensures a loop-free topology and rapid convergence in case of link failures.

OSPF is a link-state routing protocol that calculates the shortest path to a destination based on a SPF (Shortest Path First) algorithm.

EIGRP is a Cisco proprietary routing protocol that uses a composite metric based on bandwidth, delay, reliability, and load to determine the best path.

VLSM allows the use of different subnet mask lengths in the same IP network, optimizing IP address allocation.

BGP is an exterior gateway protocol used for routing between different autonomous systems. It is critical for Internet routing.

ARP poisoning is a method used by attackers to associate their MAC address with the IP address of another device, leading to traffic interception.

GRE is a tunneling protocol that encapsulates a wide variety of network layer protocols inside point-to-point connections.

The Session layer manages sessions (connections) between applications. It establishes, maintains, and terminates communication sessions.

CIDR is a method of allocating IP addresses and routing IP packets based on variable-length subnet masking, improving the efficiency of address space usage.