100+ Senior Network Engineer Interview Questions and Answers

Optimizing network physically involves organizing cables, using proper equipment, and ensuring efficient airflow.

• Organize cables neatly to prevent tangling and interference

• Use high-quality equipment to minimize downtime and maximize performance

• Ensure proper airflow to prevent overheating and maintain optimal network performance

VXLAN encapsulates Layer 2 traffic in Layer 3 packets for transport over an IP network. ACI fabric uses VXLAN to provide network virtualization.

• VXLAN encapsulates Layer 2 traffic in Layer 3 packets

• VXLAN uses a 24-bit identifier called a VXLAN Network Identifier (VNI) to identify the virtual network

• ACI fabric uses VXLAN to provide network virtualization

• ACI fabric uses a spine-leaf architecture for packet forwarding

• In ACI fabric, packets are encapsulated in VXLAN and forwarded ...read more

LAN stands for Local Area Network, a network of interconnected devices within a limited area. VLAN stands for Virtual Local Area Network, a logical grouping of devices within a LAN.

• LAN is a network of devices within a limited area, typically a single building or campus.

• VLAN is a logical grouping of devices within a LAN, allowing for segmentation and isolation of network traffic.

• LAN uses physical connections like Ethernet cables, while VLAN uses virtual connections configured ...read more

Inter VLAN routing is the process of forwarding network traffic between different VLANs.

• Inter VLAN routing allows communication between devices in different VLANs.

• It is typically done using a router or a layer 3 switch.

• Each VLAN has its own subnet and IP address range.

• Inter VLAN routing helps in segmenting network traffic for security and performance reasons.

Port forwarding is the process of redirecting network traffic from one IP address and port number combination to another.

• It allows external devices to access services on a private network

• It is commonly used for remote access, gaming, and hosting websites

• It involves configuring a router or firewall to forward traffic to a specific device on the network

• It can be a security risk if not configured properly

DNS is a system that translates domain names to IP addresses, while DHCP is a protocol that assigns IP addresses to devices on a network.

• DNS stands for Domain Name System and is used to translate domain names (like www.example.com) to IP addresses (like 192.168.1.1).

• DHCP stands for Dynamic Host Configuration Protocol and is used to automatically assign IP addresses, subnet masks, and other network configuration parameters to devices on a network.

• DNS is essential for browsing ...read more

DR BDR section process in spanning tree involves the election of designated and backup designated routers.

• DR BDR stands for Designated Router and Backup Designated Router.

• In a multi-access network, DR and BDR are elected to reduce the number of adjacencies and optimize network traffic.

• The DR is responsible for sending updates to all other routers in the network.

• The BDR takes over if the DR fails.

• Election process is based on priority, with the highest priority router becoming ...read more

TCP/IP protocol suites are a set of communication protocols used for connecting network devices.

• TCP/IP is a suite of protocols that includes TCP, IP, UDP, ICMP, ARP, and others.

• TCP is responsible for establishing a reliable connection between two devices.

• IP is responsible for routing data packets between devices.

• UDP is a connectionless protocol used for sending small amounts of data.

• ICMP is used for error reporting and diagnostic purposes.

• ARP is used for mapping a network add...read more

BGP attributes are used to influence the path selection process in BGP routing.

• BGP attributes include AS_PATH, NEXT_HOP, LOCAL_PREF, etc.

• AS_PATH attribute shows the path the route has taken through ASes.

• NEXT_HOP attribute specifies the next hop IP address for the route.

• LOCAL_PREF attribute is used to influence outbound traffic.

• Examples of BGP attributes manipulation include AS_PATH prepending and setting LOCAL_PREF.

A route reflector is a feature in BGP that helps reduce the number of IBGP peerings required in a network.

• Route reflectors help in reducing the number of IBGP peerings in a network by allowing a route reflector to reflect routes to other routers.

• They are used in large-scale networks to avoid the full mesh IBGP requirement.

• Route reflectors can be configured in a hierarchy to further optimize route reflection in the network.

Firewalls are network security devices that monitor and control incoming and outgoing network traffic.

• Firewalls act as a barrier between internal and external networks, filtering traffic based on predefined rules.

• They can be hardware or software-based, and can be configured to allow or block specific types of traffic.

• Firewalls can protect against unauthorized access, malware, and other network threats.

• Examples of firewalls include Cisco ASA, Palo Alto Networks, and pfSense.

VLAN is a logical grouping of devices on a network, based on function, department, or application.

• VLANs improve network security and performance by separating traffic.

• Types of VLAN include default VLAN, data VLAN, voice VLAN, management VLAN, and guest VLAN.

• Default VLAN is VLAN 1 and is used for all untagged traffic.

• Data VLAN is used for user data traffic.

• Voice VLAN is used for VoIP traffic.

• Management VLAN is used for network management traffic.

• Guest VLAN is used for guest ac...read more

I have extensive experience in troubleshooting complex network issues.

• I have a deep understanding of network protocols and technologies.

• I am skilled in using network diagnostic tools such as Wireshark and tcpdump.

• I have experience troubleshooting issues with routing, switching, firewalls, and VPNs.

• I am able to analyze network traffic and identify the root cause of issues.

• I have experience working with vendors to resolve complex issues.

• I am able to document troubleshooting ste...read more

Day to day activities of a Senior Network Engineer involve troubleshooting network issues, implementing network upgrades, and monitoring network performance.

• Troubleshooting network issues such as connectivity problems, slow performance, or security breaches

• Implementing network upgrades and expansions to improve performance and scalability

• Monitoring network performance and security to ensure optimal operation

• Collaborating with other IT teams to plan and implement network chang...read more

ACI stands for Application Centric Infrastructure, a software-defined networking solution. Firewall is a network security system that monitors and controls incoming and outgoing network traffic.

• ACI is a software-defined networking solution that provides centralized automation and policy-driven application profiles.

• ACI helps in simplifying network operations, improving security, and enabling application agility.

• Firewall is a network security system that acts as a barrier betwe...read more

Expected salary for a Senior Network Engineer depends on experience, location, and company size.

• Salary expectations can vary based on years of experience in the field.

• Location plays a significant role in determining salary, with higher salaries typically found in major cities.

• Company size can also impact salary, with larger companies often offering higher compensation packages.

• Research industry standards and use online resources to determine a competitive salary range.

• Conside...read more

MPLS is a protocol used to route data across a network, while lease line is a dedicated connection between two points.

• MPLS is a protocol used to create virtual private networks (VPNs) over a service provider's network

• Lease line is a dedicated connection between two points, typically provided by a telecommunications company

• MPLS allows for traffic engineering and Quality of Service (QoS) capabilities

• Lease line offers guaranteed bandwidth and low latency

• MPLS is more flexible and...read more

A syslog server is a centralized logging server that collects and stores log messages from various network devices.

• Syslog servers receive log messages from network devices such as routers, switches, firewalls, and servers.

• They store these log messages in a centralized location for easy monitoring, analysis, and troubleshooting.

• Syslog servers can also forward log messages to other systems for further processing or alerting.

• Popular syslog server software includes syslog-ng, rsy...read more

Subnetting is the process of dividing a network into smaller subnetworks.

• Subnetting helps in efficient utilization of IP addresses.

• It improves network performance and security.

• Subnetting is done by borrowing bits from the host portion of an IP address.

• CIDR notation is used to represent subnet masks.

• Example: 192.168.1.0/24 represents a network with 256 IP addresses.

OSPF (Open Shortest Path First) is a routing protocol used to exchange routing information within a single autonomous system.

• OSPF is a link-state protocol

• It uses Dijkstra's algorithm to calculate the shortest path

• It supports VLSM (Variable Length Subnet Masking)

• It uses multicast to send updates

• It has a hierarchical design with areas

• Example: OSPF is commonly used in enterprise networks

Routing and switching technologies are essential components of network infrastructure.

• Understanding of routing protocols such as OSPF, EIGRP, BGP

• Knowledge of VLANs, STP, VTP for switching

• Experience with Cisco routers and switches

• Troubleshooting network connectivity issues

• Implementing network security measures

A SCADA server is a computer system that is used to control and monitor industrial processes in real-time.

• SCADA stands for Supervisory Control and Data Acquisition

• SCADA servers collect data from sensors and equipment in industrial settings

• They allow operators to remotely monitor and control processes

• SCADA servers are critical for industries like manufacturing, energy, and water treatment

• Examples of SCADA software include Wonderware, Ignition, and Siemens WinCC

OSPF routing in broadcast is a method of routing in which OSPF packets are sent to all devices on a network segment.

• OSPF packets are sent to all devices on a network segment, regardless of whether they need the information or not.

• This method is used in networks where there are multiple routers on a single segment.

• Broadcast OSPF packets are sent using multicast addresses.

• This method can be less efficient than other OSPF routing methods, such as point-to-point or non-broadcast....read more

BGP protocol states include Idle, Connect, Active, OpenSent, OpenConfirm, Established.

• Idle state is the initial state where BGP is not running.

• Connect state is when BGP is trying to establish a TCP connection.

• Active state is when BGP is waiting for a TCP connection to be completed.

• OpenSent state is when BGP has sent an Open message to a peer.

• OpenConfirm state is when BGP has received an Open message and is waiting for a Keepalive message.

• Established state is when BGP has succ...read more

IPSec Tunnel is a secure communication channel that uses IPsec protocol to encrypt and authenticate data transmitted over a network.

• IPSec Tunnel is used to establish a secure connection between two networks or devices.

• It provides confidentiality, integrity, and authentication for data transmission.

• IPSec Tunnel encrypts the data packets at the sending end and decrypts them at the receiving end.

• It uses IPsec protocol suite which includes protocols like Authentication Header (AH...read more

A network is a collection of interconnected devices that can communicate and share resources.

• A network allows devices to connect and communicate with each other.

• It enables the sharing of resources such as files, printers, and internet access.

• Networks can be wired or wireless.

• Examples of networks include local area networks (LANs), wide area networks (WANs), and the internet.

Networks are essential for connecting devices and enabling communication and data sharing.

• Facilitates communication between devices

• Enables data sharing and collaboration

• Provides access to resources and services

• Supports remote access and mobility

• Increases efficiency and productivity

An EWO is an Emergency Work Order, a request for immediate action to address a critical issue.

• EWOs are typically used in urgent situations where immediate action is required to prevent further damage or downtime.

• Examples of EWOs include network outages, security breaches, or critical hardware failures.

• EWOs are prioritized over regular work orders due to their urgent nature.

RSTP is a protocol used to prevent loops in a network by dynamically disabling ports.

• RSTP stands for Rapid Spanning Tree Protocol

• It is an improvement over STP (Spanning Tree Protocol)

• RSTP uses port roles (root, designated, alternate, backup) to determine which ports should be active

• It also uses port states (discarding, learning, forwarding) to prevent loops

• RSTP can detect and respond to topology changes faster than STP

BGP (Border Gateway Protocol) and OSPF (Open Shortest Path First) are routing protocols used in networking to determine the best path for data to travel.

• BGP is an exterior gateway protocol used to exchange routing information between different autonomous systems.

• OSPF is an interior gateway protocol used to determine the best path for data within a single autonomous system.

• BGP uses TCP port 179 for communication, while OSPF uses IP protocol 89.

• BGP is a path vector protocol, wh...read more

STP (Spanning Tree Protocol) and RSTP (Rapid Spanning Tree Protocol) are network protocols used to prevent loops in Ethernet networks.

• STP is a network protocol that ensures a loop-free topology in Ethernet networks by blocking redundant paths.

• RSTP is an updated version of STP that provides faster convergence in the event of network changes.

• STP and RSTP both work by electing a root bridge and calculating the shortest path to it.

• STP has a slower convergence time compared to RST...read more

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

• BGP attributes include AS Path, Next Hop, Local Preference, Weight, and Origin.

• AS Path is a list of AS numbers that the route has traversed.

• Next Hop is the IP address of the next router to reach the destination.

• Local Preference is used to prefer one route over another within the same AS.

• Weight is a Cisco-specific attribute used to influence route selection.

• Origin indicates how BGP learn...read more

OSPF LSA types include Router LSA, Network LSA, Summary LSA, and ASBR Summary LSA.

• Router LSA: Generated by each router to describe its directly connected links.

• Network LSA: Generated by DR to describe the network and its attached routers.

• Summary LSA: Generated by ABR to advertise routes from one area to another.

• ASBR Summary LSA: Generated by ASBR to advertise external routes into OSPF domain.

VSS switch is a feature in Cisco switches for combining multiple physical switches into a single logical switch, while VPC is a feature for creating a loop-free topology in a data center network.

• VSS switch combines multiple physical switches into a single logical switch, providing higher availability and simplified network management.

• VPC (Virtual Port Channel) is a feature that allows links that are physically connected to two different switches to appear as a single port cha...read more

Stateful firewall keeps track of the state of active connections and makes decisions based on the context of the traffic.

• Stateful firewall inspects incoming and outgoing packets and compares them to a database of trusted connections.

• It allows or blocks traffic based on the state of the connection and predefined rules.

• Examples include Cisco ASA, Palo Alto Networks, and Fortinet firewalls.

Tools & software functioning involves monitoring, troubleshooting, and optimizing network performance using various tools and software.

• Monitoring network traffic and performance using tools like Wireshark, SolarWinds, and Nagios

• Troubleshooting network issues with tools like Ping, Traceroute, and Netcat

• Optimizing network performance with tools like Cisco Prime Infrastructure and Riverbed SteelCentral

OSPF has 8 states: Down, Init, 2-Way, ExStart, Exchange, Loading, Full, and Neighbor.

• OSPF has 8 states in the adjacency process

• Down state is when the interface is not participating in OSPF

• Init state is when the router is trying to establish a neighbor relationship

• 2-Way state is when bidirectional communication is established

• ExStart state is when routers exchange initial database information

• Exchange state is when routers exchange link-state advertisements

• Loading state is when ...read more

Path selection in BGP involves choosing the best route based on various attributes like AS path length, local preference, and origin type.

• BGP uses a combination of attributes like AS path length, local preference, and origin type to select the best path.

• The path with the shortest AS path length is preferred in BGP route selection.

• Local preference is used to influence outbound traffic by assigning higher preference to certain routes.

• Origin type (IGP, EGP, or incomplete) is ano...read more

SD-WAN stands for Software-Defined Wide Area Network, a technology that simplifies the management and operation of a WAN by decoupling the networking hardware from its control mechanism.

• Utilizes software-defined networking (SDN) principles to dynamically direct traffic across the WAN

• Improves network performance, reduces costs, and enhances security

• Allows for centralized control and automation of network management tasks

• Supports multiple connection types including MPLS, broadb...read more

SCADA stands for Supervisory Control and Data Acquisition, a system used for monitoring and controlling industrial processes.

• SCADA systems are used in industries such as energy, water treatment, manufacturing, and transportation.

• They consist of sensors, controllers, and a human-machine interface for operators to monitor and control processes.

• SCADA systems help improve efficiency, reduce downtime, and enhance safety in industrial operations.

• Examples of SCADA systems include mo...read more

IPsec is a protocol suite used to secure internet protocol (IP) communications by authenticating and encrypting each IP packet of a communication session.

• IPsec provides security services at the IP layer by enabling secure communication over the Internet.

• It uses encryption algorithms to ensure data confidentiality and authentication protocols to verify the identity of communicating parties.

• IPsec operates in two modes: Transport mode, where only the payload of the IP packet is ...read more

OSI model has 7 layers while TCP/IP model has 4 layers.

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

• TCP/IP model has 4 layers: Network Interface, Internet, Transport, Application

• OSI model is a theoretical model while TCP/IP model is a practical implementation

The network is a system of interconnected devices and communication pathways that allow for the exchange of data and information.

• A network can be wired or wireless

• Devices in a network can include computers, servers, routers, switches, and more

• Networks can be local (LAN), wide area (WAN), or global (Internet)

• Protocols like TCP/IP govern how data is transmitted over a network

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

• DHCP client sends a broadcast request for an IP address to DHCP server

• DHCP server receives the request and offers an IP address

• DHCP client accepts the offer and requests the IP address

• DHCP server assigns the IP address to the client

• DHCP client acknowledges the assignment

FTTx stands for Fiber to the x, where x can be home, premises, building, curb, or node.

• FTTx is a broadband network architecture that uses fiber optic cables to deliver high-speed internet access.

• The 'x' in FTTx can refer to various endpoints such as home, premises, building, curb, or node.

• FTTx offers faster and more reliable internet connections compared to traditional copper-based networks.

• Examples of FTTx technologies include FTTH (Fiber to the Home), FTTP (Fiber to the Pre...read more

SIA (Stuck In Active) is a mechanism in EIGRP to prevent routing loops by marking a route as 'stuck' if a feasible successor is not found.

• SIA occurs when a router is unable to find a feasible successor for a route during a topology change.

• During SIA, the router marks the route as 'stuck' and queries its neighbors for a new path.

• This prevents routing loops by temporarily blocking the affected route until a new feasible successor is found.

The network switch issue can be caused by various factors such as hardware failure, configuration errors, or network congestion.

• Check the switch logs for any error messages

• Verify the switch configuration and ensure it is correct

• Check the network traffic and identify any congestion issues

• Perform hardware diagnostics to identify any faulty components

• Consider upgrading the switch firmware or hardware if necessary