100+ Network Support Engineer Interview Questions and Answers

A protocol is a set of rules that governs the communication between devices in a network. There are several types of protocols.

• A protocol defines the format, timing, sequencing, and error control of data transmission.

• Protocols can be categorized into network protocols, transport protocols, and application protocols.

• Examples of network protocols include IP (Internet Protocol), ICMP (Internet Control Message Protocol), and ARP (Address Resolution Protocol).

• Transport protocols i...read more

The protocol with the lowest AD value is OSPF (Open Shortest Path First).

• AD (Administrative Distance) is a value used by routers to determine the best path for forwarding packets.

• Lower AD value indicates a more preferred route.

• OSPF has an AD value of 110, which is lower than other routing protocols like RIP (120) and EIGRP (90).

DHCP is a network protocol that automatically assigns IP addresses to devices on a network.

• DHCP stands for Dynamic Host Configuration Protocol.

• It allows devices to obtain IP addresses, subnet masks, default gateways, and other network configuration settings automatically.

• DHCP uses a client-server model, where the DHCP server assigns IP addresses to clients.

• The DHCP server maintains a pool of available IP addresses and leases them to clients for a specific period of time.

• When ...read more

The layers that call to the heart of OSI are the Transport layer and the Application layer.

• The Transport layer is responsible for the end-to-end delivery of data and ensures reliable communication between hosts.

• The Application layer provides services directly to the end-user and includes protocols like HTTP, FTP, SMTP, etc.

• These layers interact with the heart of the OSI model, which is the core of the network architecture.

• The heart of OSI represents the central processing and...read more

Protocols that work with Application layers include HTTP, FTP, SMTP, DNS, and SNMP.

• HTTP (Hypertext Transfer Protocol) is used for web browsing and communication between web servers and clients.

• FTP (File Transfer Protocol) is used for transferring files between a client and a server.

• SMTP (Simple Mail Transfer Protocol) is used for sending and receiving email messages.

• DNS (Domain Name System) is used for translating domain names into IP addresses.

• SNMP (Simple Network Management...read more

The OSI model is a conceptual framework that standardizes the functions of a communication system into seven layers.

• Layer 1 (Physical): Deals with the physical transmission of data over the network.

• Layer 2 (Data Link): Provides error-free transmission of data frames between nodes on the same network.

• Layer 3 (Network): Handles routing and logical addressing to enable data transfer between different networks.

• Layer 4 (Transport): Ensures reliable delivery of data by segmenting a...read more

The tool commonly used for configuring routers is a command-line interface (CLI).

• Command-line interface (CLI) is the primary tool for configuring routers.

• CLI allows network engineers to enter commands to configure various settings on the router.

• Examples of CLI tools for router configuration include Cisco IOS CLI, Juniper Junos CLI, and Huawei VRP CLI.

AD stands for Active Directory, which is a directory service used in Windows environments. Range refers to a specific set of values or a span of numbers.

• AD is a centralized database that stores information about network resources, such as users, computers, and groups.

• It provides authentication and authorization services, allowing users to access resources based on their permissions.

• AD uses a hierarchical structure with domains, trees, and forests to organize and manage networ...read more

The main function of the Root bridge switch is to control the flow of data traffic in a spanning tree network.

• The Root bridge switch is elected as the central point of the spanning tree network.

• It determines the shortest path for data traffic to reach all other switches in the network.

• The Root bridge switch sends Bridge Protocol Data Units (BPDUs) to other switches to exchange information and maintain the spanning tree topology.

• It helps prevent loops and ensures a loop-free n...read more

SSH port number is 22. SSH service is used for secure remote access and secure file transfer.

• SSH port number is 22 by default

• SSH stands for Secure Shell

• SSH service provides secure remote access to servers

• It encrypts the data transmitted over the network

• SSH service is used for secure file transfer (SFTP) and remote command execution

• It provides authentication and encryption for secure communication

I have worked on various router devices and vendors.

• Cisco routers (e.g. Cisco 2900 series)

• Juniper routers (e.g. Juniper MX series)

• Huawei routers (e.g. Huawei NE series)

• MikroTik routers (e.g. MikroTik RB series)

yum is a package manager for Linux that automates software installation, updates, and removal.

• yum stands for Yellowdog Updater Modified

• It is used to manage packages and dependencies in Red Hat-based Linux distributions

• It can be used to install, update, and remove software packages

• It automatically resolves dependencies and downloads necessary packages

• Examples of yum commands include 'yum install', 'yum update', and 'yum remove'

VLANs are used to logically segment a network, improving security, performance, and manageability. The range of VLANs is from 1 to 4094.

• VLANs provide network segmentation, allowing different groups of devices to be isolated from each other.

• They enhance security by controlling access between VLANs using access control lists (ACLs).

• VLANs improve network performance by reducing broadcast traffic and optimizing network traffic flow.

• They simplify network management by allowing adm...read more

Use network automation tools like Ansible or Python scripts to quickly create multiple networks.

• Utilize network automation tools like Ansible or Python scripts

• Create templates for network configurations to speed up the process

• Use network virtualization technologies like VLANs or VXLANs to segment networks

• Leverage cloud-based network services for rapid deployment

• Consider using network automation platforms like Cisco DNA Center or Juniper Contrail

TCP/IP stack is a set of protocols used for communication over the internet, while OSI Model is a conceptual framework for understanding network communication.

• TCP/IP stack is a practical implementation of networking protocols used for communication over the internet.

• It consists of four layers: Application, Transport, Internet, and Link.

• Each layer has its own set of protocols and functions, such as HTTP, TCP, IP, and Ethernet.

• OSI Model, on the other hand, is a theoretical fram...read more

Public IP is a unique address assigned to a device on the internet, while Private IP is used within a local network.

• Public IP is globally unique and can be accessed from anywhere on the internet.

• Private IP is used within a local network and is not accessible from the internet.

• Public IP is assigned by the Internet Service Provider (ISP) to identify a device on the internet.

• Private IP is assigned by a local network administrator to identify devices within the network.

• Public IP ...read more

Spanning tree is a protocol that prevents loops in a network by selectively blocking redundant paths.

• Spanning tree protocol (STP) is used to prevent network loops

• It works by selectively blocking redundant paths

• STP elects a root bridge and calculates the shortest path to it

• It uses Bridge Protocol Data Units (BPDUs) to communicate with other switches

• STP can be configured with different modes such as Rapid Spanning Tree Protocol (RSTP) and Multiple Spanning Tree Protocol (MSTP)

DNS uses port number 53. It works by translating domain names into IP addresses and vice versa.

• DNS stands for Domain Name System.

• Port number 53 is used for both TCP and UDP protocols.

• DNS works by resolving domain names to their corresponding IP addresses.

• It uses a hierarchical distributed database system.

• DNS queries and responses are sent over port 53.

• DNS operates through a client-server model.

• Example: When you type a website URL, DNS translates it to the IP address of the se...read more

Switching concepts refer to the functionalities and states of network switches.

• Switching is the process of forwarding data packets between network devices.

• Switches operate at the data link layer of the OSI model.

• Switches use MAC addresses to forward packets to the correct destination.

• Switches can operate in different modes such as access, trunk, and VLAN.

• Switches can also perform functions such as port security, QoS, and STP.

• Examples of switches include Cisco Catalyst, Junipe...read more

IPv4 address is a unique numerical label assigned to each device connected to a computer network using Internet Protocol version 4.

• IPv4 address is a 32-bit address used to identify devices on a network.

• It is written in decimal format with four numbers separated by periods (e.g. 192.168.1.1).

• Each number in the address can range from 0 to 255.

• IPv4 addresses are used for communication and routing of data packets over a network.

No, DHCP servers assign IP addresses to devices within a local network, not to devices connected to the internet.

• DHCP servers assign IP addresses to devices within a local network

• Devices connected to the internet may receive IP addresses from their ISP

• DHCP servers help manage IP address allocation and configuration

Apache server is a web server software used to serve web pages and applications.

• Apache server is open-source software

• It is used to host websites and web applications

• It supports multiple programming languages like PHP, Python, and Perl

• It can be configured to handle SSL/TLS encryption for secure connections

• Apache server is highly customizable and extensible with modules

• Examples of websites using Apache server include Airbnb, Apple, and IBM

BGP is a routing protocol used in large-scale networks to exchange routing information between autonomous systems.

• BGP stands for Border Gateway Protocol.

• It is used to connect different autonomous systems (AS) on the internet.

• BGP allows routers in different ASs to exchange routing information and make informed decisions on the best paths for data transmission.

• It is a path-vector protocol that considers multiple factors like network policies, path attributes, and performance me...read more

EIGRP is a Cisco proprietary routing protocol that uses advanced distance-vector algorithm for efficient routing in IP networks.

• EIGRP stands for Enhanced Interior Gateway Routing Protocol.

• It is used to exchange routing information between routers in a network.

• EIGRP uses a combination of distance-vector and link-state routing protocols.

• The port number for EIGRP is 88.

Networking involves the communication between devices to share resources and information. TCP and UDP are protocols used for data transmission, VLANs separate networks, wireless networks use radio waves, and servers provide resources to clients.

• Networking is the practice of connecting devices to share resources and information

• TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are protocols used for data transmission over networks

• VLANs (Virtual Local Area Net...read more

Configuring telnet and ssh, understanding OSI module and DHCP

• To configure telnet, enable the telnet service on the device and set a password for access

• To configure ssh, generate a public and private key pair and enable ssh service on the device

• OSI module is a conceptual model that describes how data is transmitted over a network

• DHCP is a protocol that automatically assigns IP addresses to devices on a network

STP (Spanning Tree Protocol) is a network protocol that prevents loops in Ethernet networks by creating a loop-free logical topology.

• STP is used to prevent broadcast storms and network congestion.

• It works by electing a root bridge and calculating the shortest path to the root bridge for each network segment.

• STP uses Bridge Protocol Data Units (BPDU) to exchange information between switches.

• It employs a tree-like structure with designated ports and blocked ports to ensure a lo...read more

2G, 3G, and 5G are different generations of mobile network technology.

• 2G refers to second-generation mobile network technology, which primarily provided voice and basic data services.

• 3G refers to third-generation mobile network technology, which introduced faster data speeds and enabled mobile internet access.

• 5G refers to fifth-generation mobile network technology, which offers significantly faster data speeds, lower latency, and supports advanced technologies like Internet o...read more

The HTTPS port number is 443.

• HTTPS uses port 443 for secure communication.

• It is the default port for secure HTTP connections.

• HTTPS encrypts data using SSL/TLS protocols.

• Examples: https://www.example.com:443 or https://192.168.0.1:443

There are multiple ways to transfer data in CCNA, including wired and wireless methods.

• Data transfer methods in CCNA include Ethernet, Wi-Fi, Bluetooth, and cellular networks.

• Ethernet is a common wired method used for data transfer in CCNA.

• Wi-Fi allows for wireless data transfer over a local network.

• Bluetooth is used for short-range wireless data transfer between devices.

• Cellular networks enable data transfer over mobile networks.

IP stands for Internet Protocol, which is a logical address used to identify devices on a network.

• IP is a unique identifier assigned to each device connected to a network.

• It allows devices to communicate with each other by routing data packets.

• There are two versions of IP - IPv4 and IPv6.

• IPv4 addresses are 32 bits long and written in decimal format (e.g. 192.168.1.1).

• IPv6 addresses are 128 bits long and written in hexadecimal format (e.g. 2001:0db8:85a3:0000:0000:8a2e:0370:73...read more

A port channel is a method used to bundle multiple physical ports together to increase bandwidth and redundancy. A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on predetermined security rules.

• Port channel is used to increase bandwidth and redundancy by bundling multiple physical ports together

• Firewall is a network security device that monitors and controls network traffic based on security rules

• Port channel is co...read more

There are two main types of modes in router configuration: user mode and privileged mode.

• User mode: Limited access to view router status and basic configurations.

• Privileged mode: Full access to configure, manage, and troubleshoot the router.

• Examples: 'show' command in user mode, 'configure terminal' command in privileged mode.

A firewall is a network security system that monitors and controls incoming and outgoing network traffic.

• Firewalls can be hardware or software-based.

• They use a set of rules to determine whether to allow or block traffic.

• Firewalls can be configured to block specific types of traffic, such as certain websites or protocols.

• They can also be configured to allow traffic from specific IP addresses or domains.

• Firewalls can help prevent unauthorized access to a network and protect aga...read more

Routing is the process of selecting the best path for network traffic to reach its destination.

• Routing helps in efficient and effective communication between devices on a network.

• It involves analyzing network topology and selecting the best path based on factors like distance, speed, and cost.

• Routing protocols like OSPF, BGP, and EIGRP are used to automate the process of routing.

• Routing is essential for the internet to function, as it enables communication between different n...read more

STP stands for Spanning Tree Protocol.

• STP is a network protocol used to prevent loops in Ethernet networks.

• It works by creating a loop-free logical topology by blocking redundant paths.

• STP elects a root bridge and calculates the shortest path to it for each network segment.

• It uses Bridge Protocol Data Units (BPDU) to exchange information between switches.

• STP is defined by the IEEE 802.1D standard.

VLAN is a virtual LAN that allows network devices to communicate as if they were on the same physical network. ABR router is a router that connects two or more areas in a network.

• VLAN separates a physical network into multiple logical networks

• Devices in different VLANs cannot communicate without a router

• ABR router connects different areas in a network, such as OSPF areas or IS-IS levels

• ABR router maintains separate routing tables for each area it connects

I believe in continuous learning and self-improvement, and I understand the importance of having access to the latest technology and infrastructure.

• I would like to know more about the current infrastructure and what limitations it has in terms of technology

• I would explore alternative solutions such as online courses, certifications, and attending conferences to stay up-to-date with the latest technology

• I would also suggest discussing the issue with management and proposing a ...read more

The number of VLANs that can be configured in an L2 switch depends on the specific model and manufacturer, but typically ranges from 4 to 4096.

• The number of VLANs supported by an L2 switch is determined by the switch's hardware capabilities and software limitations.

• Most L2 switches support a minimum of 4 VLANs and a maximum of 4096 VLANs.

• Higher-end switches may support even more VLANs, while lower-end switches may have a lower limit.

• Some switches may have restrictions on the ...read more

DHCP is a network protocol that assigns IP addresses to devices. DNS translates domain names to IP addresses. IP address is a unique identifier for devices. CDN is a content delivery network.

• DHCP - Dynamic Host Configuration Protocol assigns IP addresses to devices on a network

• DNS - Domain Name System translates domain names to IP addresses

• IP address - Internet Protocol address is a unique identifier for devices on a network

• CDN - Content Delivery Network is a distributed netw...read more

Public IP is the address assigned to a device on the internet, while private IP is the address assigned to a device on a local network.

• Public IP is unique and globally routable, allowing devices to communicate over the internet.

• Private IP is used within a local network and is not accessible from the internet.

• Public IP is assigned by the Internet Service Provider (ISP), while private IP is assigned by the local network's router.

• Public IP can be static or dynamic, while private...read more

The packet flow of the dr and bdr election is the process by which routers in a network determine the designated router and backup designated router.

• DR and BDR are elected in OSPF networks to reduce the amount of OSPF traffic and maintain network stability.

• The election process begins with routers exchanging Hello packets to establish neighbor relationships.

• Routers with higher OSPF priority or higher router ID are preferred for the DR and BDR roles.

• The DR and BDR multicast OSP...read more

Router configurations involve setting up and managing network devices to ensure efficient and secure communication.

• Router configurations involve configuring IP addresses, subnet masks, and default gateways.

• Setting up access control lists (ACLs) to control network traffic.

• Enabling routing protocols such as OSPF or BGP for dynamic routing.

• Configuring NAT (Network Address Translation) to allow private IP addresses to access the internet.

• Implementing security measures like firewa...read more

DHCP DORA process is the sequence of steps followed by a client to obtain an IP address from a DHCP server.

• DORA stands for Discover, Offer, Request, and Acknowledge.

• Discover: Client broadcasts a DHCP Discover message to find available DHCP servers.

• Offer: DHCP servers respond with DHCP Offer messages containing IP address lease information.

• Request: Client selects one DHCP Offer and sends a DHCP Request message to request the offered IP address.

• Acknowledge: DHCP server sends a ...read more

DTP (Dynamic Trunking Protocol) is a Cisco proprietary protocol used to negotiate trunking between switches.

• DTP is used to automatically negotiate trunking on a link between Cisco switches.

• It allows switches to dynamically form trunk links without manual configuration.

• DTP operates in three modes: dynamic auto, dynamic desirable, and trunk.

• Dynamic auto mode waits for the other end to initiate trunking.

• Dynamic desirable mode actively tries to form a trunk.

• Trunk mode actively fo...read more

The HTTP port number is 80.

• The default port number for HTTP is 80.

• It is used for communication between web servers and clients.

• Other common port numbers for HTTP include 8080 and 8888.

VTP (VLAN Trunking Protocol) is a Cisco proprietary protocol used to manage VLAN configurations across a network. VLANs are virtual LANs that separate broadcast domains.

• VTP is used to synchronize VLAN information across switches in a network

• It helps in reducing the administrative overhead of manually configuring VLANs on each switch

• VLANs are used to logically segment a network into separate broadcast domains

• VLANs improve network performance and security by isolating traffic