800+ Network Engineer Interview Questions and Answers

Check for alternate path, isolate the failed link, replace the link or switch.

• Check for alternate path in the ring topology

• Isolate the failed link by disabling it

• Replace the failed link or switch

• Verify connectivity and network stability

Yes, I am comfortable with cloud technologies and have experience working with various cloud platforms.

• I have experience working with AWS, Azure, and Google Cloud Platform

• I am familiar with cloud networking concepts such as VPC, VPN, and CDN

• I have implemented cloud-based solutions for scalability and redundancy

• I am proficient in using cloud monitoring and management tools

Subnetting is dividing a network into smaller subnetworks. There are two types of routing: static and dynamic. Static routing is manually configured by the network administrator. The subnet mask of /27 is 255.255.255.224. STP is a protocol used to prevent loops in a network. Etherchannel is a technique used to combine multiple physical links into a single logical link. VLAN is a logical grouping of devices in a network. Looping in switches is when a packet is forwarded endles...read more

A router is a networking device that forwards data packets between computer networks.

• Routers operate at the network layer of the OSI model.

• They use routing tables to determine the best path for data packets to travel.

• Routers can connect different types of networks, such as LANs and WANs.

• Examples of routers include Cisco, Juniper, and TP-Link.

• Routers can provide security features such as firewalls and VPNs.

The network architecture of my previous organization consisted of a centralized data center with multiple branch offices connected via MPLS.

• Centralized data center with redundant core switches and firewalls

• Branch offices connected via MPLS for secure communication

• Implemented VLANs to segregate network traffic

• Configured and maintained routers, switches, and firewalls

• Monitored network performance and security incidents

Yes, I have experience with cloud technologies such as Azure.

• I have worked with Azure cloud services in previous projects

• Familiar with setting up virtual machines, storage, and networking in Azure

• Experience with Azure DevOps for continuous integration and deployment

A /29 subnet has 6 usable host addresses.

• A /29 subnet has a subnet mask of 255.255.255.248.

• The subnet mask leaves 3 bits for host addresses.

• 2^3 = 8, but 2 addresses are reserved for network and broadcast.

• Therefore, a /29 subnet has 6 usable host addresses.

PPPoE is a protocol used to connect devices to the internet through a DSL line. WAN stands for Wide Area Network. Routers are configured to connect devices to the internet.

• PPPoE stands for Point-to-Point Protocol over Ethernet

• It is used to establish a connection between a device and an ISP through a DSL line

• WAN is a network that covers a large geographical area, such as the internet

• Routers are configured with settings such as IP address, subnet mask, default gateway, and DNS ...read more

DHCP is a network protocol that assigns IP addresses to devices. DHCP option 42 is the NTP server option, while DHCP option 40 is the NIS domain option.

• DHCP is a protocol used to automatically assign IP addresses to devices on a network.

• DHCP option 42 is used to specify the Network Time Protocol (NTP) server that the client should use.

• DHCP option 40 is used to specify the Network Information Service (NIS) domain that the client should use.

DHCP assigns IP addresses to devices on a network. Relay agent forwards DHCP messages between subnets.

• DHCP (Dynamic Host Configuration Protocol) assigns IP addresses, subnet masks, default gateways, and DNS servers to devices on a network.

• DHCP server listens for DHCP requests from clients and responds with an IP address lease.

• Relay agent is used when DHCP server and client are on different subnets. It forwards DHCP messages between subnets.

• Relay agent adds its own IP address ...read more

Explaining various SIP headers and concepts like call forking, registration, transfer, and SDP.

• Mandatory SIP headers include From, To, Call-ID, CSeq, and Via.

• Update is used to modify an existing session, while Reinvite is used to add or remove media streams.

• Call forking allows multiple devices to ring simultaneously for the same call.

• SIP registration is the process of authenticating a user agent with a SIP server.

• Call transfer involves redirecting a call to another user or de...read more

IPv6 is the successor to IPv4, with larger address space, improved security, and better support for mobile devices.

• IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses

• IPv6 has a hierarchical addressing structure, allowing for more efficient routing

• IPv6 includes built-in security features, such as IPsec

• IPv6 has better support for mobile devices, with features like mobile IP and flow labeling

BGP attributes are characteristics used to influence routing decisions in Border Gateway Protocol.

• BGP attributes are used to determine the best path for routing traffic.

• Some common BGP attributes include AS Path, Next Hop, Local Preference, and MED.

• AS Path attribute shows the path of autonomous systems that the route has traversed.

• Next Hop attribute indicates the IP address to reach the next hop for the route.

• Local Preference attribute is used to influence the path selection ...read more

Yes, I am familiar with Routing and Switching as well as Firewall.

• I have experience in configuring and troubleshooting routing protocols such as OSPF and BGP.

• I am proficient in VLANs, STP, and other switching technologies.

• I have worked with various firewall vendors such as Cisco ASA, Palo Alto, and Fortinet.

• I am knowledgeable in firewall policies, NAT, VPN, and other security features.

• I am constantly learning and keeping up with the latest technologies and best practices.

The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes the functions of a communication system into seven layers.

• The seven layers of the OSI model are: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• Each layer has a specific function and interacts with the layers above and below it.

• The Physical layer deals with the physical transmission of data, such as cables and network interfaces.

• The Data Link layer provide...read more

Traffic flow from one leaf endpoint to another leaf endpoint is achieved through spine switches.

• Traffic flows from the endpoint of one leaf switch to the spine switch.

• The spine switch then forwards the traffic to the endpoint of the other leaf switch.

• This is achieved through the use of routing protocols such as OSPF or BGP.

• The spine switches act as intermediaries between the leaf switches.

• This architecture is known as a leaf-spine network topology.

Numerous servers can be handled from a centralized way using server management tools and automation.

• Use server management tools like Ansible, Puppet, or Chef to manage servers remotely

• Automate server provisioning, configuration, and deployment processes

• Implement centralized monitoring and logging to track server performance and troubleshoot issues

• Use virtualization and containerization technologies to manage multiple servers on a single physical machine

• Implement security meas...read more

A Local Area Network (LAN) is a network that connects computers and devices within a limited area, such as a home, office, or building.

• LAN is used to share resources, such as files, printers, and internet access, among connected devices.

• It typically operates at a high data transfer rate and low error rate.

• LAN can be wired or wireless, using technologies like Ethernet or Wi-Fi.

• Examples of LAN include home networks, office networks, and school networks.

Load balancing involves distributing network traffic across multiple servers to optimize resource utilization and prevent overload.

• Parameters for load balancing include server health, server capacity, and current network traffic.

• To improve various KPIs like VDR, HOSR, Initial ERAB, CQI, and SSSR, you can adjust load balancing algorithms, optimize server performance, and monitor network traffic.

• For example, you can use round-robin, least connections, or weighted round-robin al...read more

RIP, PORT CHANNEL, IPSEC, Trunk & Access Port, OSPF are networking concepts.

• RIP (Routing Information Protocol) is a distance-vector routing protocol.

• PORT CHANNEL is a technique used to bundle multiple physical links into a single logical link.

• IPSEC (Internet Protocol Security) is a protocol suite used to secure Internet Protocol (IP) communications.

• Trunk Port carries traffic for multiple VLANs while Access Port carries traffic for a single VLAN.

• OSPF (Open Shortest Path First)...read more

To assemble a desktop, manage and set the process, follow these steps:

• Gather all necessary components such as motherboard, CPU, RAM, hard drive, power supply, etc.

• Install the CPU onto the motherboard and attach the heatsink/fan

• Insert the RAM into the appropriate slots on the motherboard

• Attach the hard drive and optical drive to the motherboard using SATA cables

• Connect the power supply to the motherboard and other components

• Install the operating system and necessary drivers

• Con...read more

To find the reliability of a link on Cisco routers, use the show interface command.

• Log in to the Cisco router using the console or Telnet/SSH.

• Enter the command 'show interface' to display the status of all interfaces on the router.

• Look for the 'input errors' and 'output errors' fields to determine the reliability of the link.

• If there are a high number of errors, the link may be unreliable and require troubleshooting.

• Other fields to look for include 'CRC errors', 'late collisi...read more

The domain created to connect VMM domains is called the Logical Switch domain.

• Logical Switch domain is created in System Center Virtual Machine Manager (VMM) to connect VMM domains.

• It is used to provide connectivity between virtual machines and physical networks.

• It allows for centralized management of virtual switches and network policies.

• Logical Switch domain can be used to create virtual networks that span multiple hosts and clusters.

• It supports network virtualization and c...read more

Radius protocol is used for authentication, authorization, and accounting in network communication.

• Radius protocol is used to authenticate users before granting access to a network.

• It also authorizes users based on their credentials and permissions.

• Radius protocol provides accounting functionality to track and monitor user activity on the network.

• It is commonly used in enterprise networks, VPNs, and wireless networks.

• Example: When a user tries to connect to a Wi-Fi network, t...read more

STP is a network protocol that prevents loops in Ethernet networks. Ping is a network utility used to test connectivity. OSI model is a framework for understanding how networks operate. IP address is a unique identifier for devices on a network. MAC address is a hardware address for network devices. ARP is a protocol used to map IP addresses to MAC addresses. RRRP is not a standard networking term.

• STP stands for Spanning Tree Protocol and is used to prevent loops in Ethernet ...read more

Static routes are manually configured while default routes are used when no other route is available.

• Static routes are manually configured by the network administrator

• Default routes are used when no other route is available

• Static routes have a higher priority than default routes

• Static routes are more specific than default routes

• Example: ip route 192.168.1.0 255.255.255.0 10.0.0.1

• Example: ip route 0.0.0.0 0.0.0.0 10.0.0.1

There are mainly three types of switches - unmanaged, managed and smart switches.

• Unmanaged switches are plug-and-play devices that require no configuration. They are ideal for small networks.

• Managed switches offer advanced features like VLAN, QoS, and security. They require configuration and are suitable for large networks.

• Smart switches are a hybrid of unmanaged and managed switches. They offer some advanced features but are easier to configure than managed switches.

• Switches...read more

To delete CTL and ITL files from a phone, access the phone's settings, navigate to the security or device administration section, and delete the files.

• Access the phone's settings

• Navigate to the security or device administration section

• Locate the CTL and ITL files

• Delete the files

OFC stands for Optical Fiber Cable, which is a type of cable made of glass or plastic fibers that transmit data using light.

• OFC is used for high-speed data transmission over long distances.

• It is commonly used in telecommunications, internet, and cable TV networks.

• OFC is more reliable and has higher bandwidth than traditional copper cables.

• Examples of OFC include single-mode fiber and multi-mode fiber.

• OFC requires specialized equipment for installation and maintenance.

There are mainly two types of CCTV cables in the market.

• The two types of CCTV cables are coaxial and twisted pair cables.

• Coaxial cables are commonly used for analog CCTV systems.

• Twisted pair cables are used for IP CCTV systems.

• Coaxial cables have better shielding and can transmit signals over longer distances.

• Twisted pair cables are cheaper and easier to install.

• Hybrid cables that combine both coaxial and twisted pair cables are also available.

OSI model is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system.

• OSI model has 7 layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• Each layer has a specific function and communicates with the adjacent layers.

• Subnetting is the process of dividing a network into smaller subnetworks to improve performance and security.

• Subnetting is done by borrowing bits from the host ...read more

To rectify a PC generating broadcast, check for misconfigured network settings, update network drivers, disable unnecessary services, and monitor network traffic.

• Check for misconfigured network settings such as incorrect IP address or subnet mask

• Update network drivers to ensure compatibility and stability

• Disable unnecessary services or applications that may be causing excessive network traffic

• Monitor network traffic using tools like Wireshark to identify the source of the bro...read more

Yes, I have hands-on experience on Fortigate Firewall.

• I have configured and managed Fortigate Firewall for multiple clients.

• I have implemented security policies, VPNs, and NAT rules on Fortigate Firewall.

• I have troubleshooted and resolved issues related to Fortigate Firewall.

• I am familiar with FortiOS and its features such as web filtering, IPS, and application control.

SIP call flow is the process of establishing, maintaining, and terminating a session initiated by Session Initiation Protocol (SIP).

• SIP INVITE message is sent from the caller to the callee

• Callee responds with a SIP 100 Trying message

• Callee sends a SIP 180 Ringing message to indicate the phone is ringing

• Callee sends a SIP 200 OK message to indicate the call is accepted

• Media negotiation takes place between the caller and callee

• Call termination is initiated by either party with ...read more

Load balancing with two ISP's connected to a router using BGP involves configuring BGP with both ISPs and setting up load balancing policies.

• Configure BGP with both ISPs on the router

• Set up load balancing policies to distribute traffic between the two ISPs

• Use BGP attributes such as AS path prepending, local preference, and MED to influence traffic flow

• Monitor and adjust the load balancing setup as needed

POP (110), SMTP (25), DNS (53), HTTPS (443) are port numbers used for email, domain name resolution, and secure web browsing.

• POP (Post Office Protocol) is used for receiving email (port 110)

• SMTP (Simple Mail Transfer Protocol) is used for sending email (port 25)

• DNS (Domain Name System) is used for domain name resolution (port 53)

• HTTPS (Hypertext Transfer Protocol Secure) is used for secure web browsing (port 443)

A payload dip after a cutover can have various implications on network performance and stability.

• A payload dip can lead to decreased network throughput and performance, affecting user experience.

• It may indicate issues with the new network configuration or equipment post-cutover.

• Troubleshooting may be required to identify and resolve the cause of the payload dip.

• Monitoring tools can help in detecting and analyzing the impact of the dip on network traffic.

• Proper documentation a...read more

MIMO stands for Multiple Input Multiple Output. It is a technology that uses multiple antennas to improve communication performance.

• MIMO technology uses multiple antennas at both the transmitter and receiver to improve data throughput and signal reliability.

• MIMO allows for multiple data streams to be transmitted simultaneously, increasing the overall capacity of a wireless network.

• MIMO is commonly used in Wi-Fi routers, 4G LTE networks, and 5G technology to enhance data speed...read more

BGP (Border Gateway Protocol) is a routing protocol used to exchange routing information between different autonomous systems (AS).

• BGP is used to exchange routing information and prefixes between different AS numbers.

• BGP helps in determining the best path for data to travel between networks.

• BGP operates on TCP port 179.

• BGP uses attributes like AS path, next hop, and local preference to make routing decisions.

• Example: BGP is commonly used by Internet Service Providers (ISPs) t...read more

TCP and IP are fundamental protocols in computer networking. They relate to the OSI model by defining the rules for communication.

• TCP (Transmission Control Protocol) is responsible for establishing and maintaining a connection between two devices, ensuring data is reliably transmitted.

• IP (Internet Protocol) is responsible for addressing and routing packets of data across networks.

• TCP and IP together form the basis of the Internet Protocol Suite, which is used for communicatio...read more

Firewalls are used to protect networks from unauthorized access and have features like packet filtering, NAT, VPN, and IDS/IPS.

• Firewalls prevent unauthorized access to a network by filtering incoming and outgoing traffic based on predefined rules.

• They can also perform Network Address Translation (NAT) to hide the internal IP addresses from external networks.

• Firewalls can establish Virtual Private Networks (VPNs) to securely connect remote users or sites to the network.

• They ca...read more

MTU stands for Maximum Transmission Unit. It is the largest size of data packet that can be transmitted over a network.

• MTU is measured in bytes.

• The default MTU size for Ethernet is 1500 bytes.

• To find the MTU size for CE/PE, you can use the ping command with the -f option to set the Do Not Fragment (DNF) bit and gradually increase the packet size until you receive a 'packet needs to be fragmented but DF set' message.

• Another way to find the MTU size is to use the traceroute com...read more

ISIS is used in fabric for routing and scalability purposes. Fabric is a network architecture that allows for high-speed, low-latency communication between devices.

• ISIS is a link-state routing protocol that is commonly used in fabric networks.

• Fabric is a network architecture that is designed to provide high-speed, low-latency communication between devices.

• Fabric networks are typically used in data centers and other high-performance computing environments.

• ISIS is used in fabri...read more

Answers to questions related to network engineering concepts.

• k values are used in EIGRP to calculate the metric of a route

• Neighborship criteria in EIGRP is the set of conditions that must be met for two routers to become neighbors

• Default route can be injected into EIGRP using the 'ip default-network' command

• ACL (Access Control List) is used to filter network traffic based on source/destination IP address, port number, etc.

• Prefix list is used to filter routes based on their pr...read more

VLAN is a virtual LAN that divides a physical network into multiple logical networks. EBGP and IBGP are different types of BGP routing protocols. OSPF is a link-state routing protocol.

• VLAN stands for Virtual Local Area Network and is used to segment a network into multiple smaller networks for better traffic management.

• EBGP (External BGP) is used between different autonomous systems, while IBGP (Internal BGP) is used within the same autonomous system.

• OSPF (Open Shortest Path ...read more

MSS in TCP refers to the maximum segment size, which is the largest amount of data that can be sent in a single TCP segment.

• MSS is negotiated during the TCP three-way handshake

• It is determined by the maximum transmission unit (MTU) of the network

• MSS can be adjusted by the sender or receiver using TCP options

• A smaller MSS can help prevent fragmentation and improve network performance

Yes, I have knowledge of Windows OS configuration.

• I am familiar with configuring network settings, such as IP addresses and DNS servers.

• I know how to manage user accounts and permissions.

• I am experienced in installing and updating software and drivers.

• I am proficient in troubleshooting common issues, such as blue screens and slow performance.

• I am knowledgeable in configuring security settings, such as firewalls and antivirus software.