90+ Senior Network Engineer Interview Questions and Answers

Different types of network cables include twisted pair, coaxial, fiber optic, and wireless.

• Twisted pair cables are commonly used in Ethernet networks and come in two types: unshielded (UTP) and shielded (STP)

• Coaxial cables are used in cable TV and broadband internet connections

• Fiber optic cables use light to transmit data and are used for high-speed, long-distance connections

• Wireless networks use radio waves to transmit data without the need for physical cables

• Other types of ...read more

The DORA process is used for IP address assignment in a network. It consists of four steps: Discover, Offer, Request, and Acknowledge.

• Discover: The client sends a broadcast message to find available DHCP servers.

• Offer: DHCP servers respond with an IP address lease offer.

• Request: The client selects an IP address and sends a request to the DHCP server.

• Acknowledge: The DHCP server acknowledges the request and assigns the IP address to the client.

IPSec is a protocol suite used to secure IP communications by authenticating and encrypting each IP packet.

• IPSec operates at the network layer of the OSI model.

• It provides data confidentiality, integrity, and authentication.

• IPSec uses two main protocols: Authentication Header (AH) and Encapsulating Security Payload (ESP).

• During tunnel formation, the following packets are exchanged: IKE Phase 1 Main Mode, IKE Phase 1 Aggressive Mode, IKE Phase 2 Quick Mode.

OSPF and BGP are routing protocols used in computer networks to determine the best path for data to travel.

• OSPF (Open Shortest Path First) is an interior gateway protocol used to route IP packets within a single autonomous system. It uses link-state routing (LSR) and Dijkstra's algorithm to determine the shortest path between two nodes.

• BGP (Border Gateway Protocol) is an exterior gateway protocol used to route data between different autonomous systems. It uses path-vector rou...read more

The important topologies for networks include star, bus, ring, mesh, and hybrid.

• Star topology: All devices are connected to a central hub or switch.

• Bus topology: All devices are connected to a single cable.

• Ring topology: Devices are connected in a circular manner.

• Mesh topology: Each device is connected to every other device.

• Hybrid topology: Combination of two or more topologies.

VMM integration in ACI allows seamless communication between virtual and physical networks

• VMM integration in ACI enables automation and orchestration of network policies across virtual and physical environments

• It helps in maintaining consistency and reducing errors in network configurations

• Examples of VMMs include VMware vSphere, Microsoft Hyper-V, and KVM

• VMM integration is required to ensure efficient communication and management of virtualized workloads in the data center

There are several types of networks, including LAN, WAN, MAN, WLAN, PAN, SAN, and CAN.

• Local Area Network (LAN) - a network that covers a small geographical area, such as an office building.

• Wide Area Network (WAN) - a network that spans a large geographical area, such as connecting multiple offices across different cities.

• Metropolitan Area Network (MAN) - a network that covers a larger area than a LAN but smaller than a WAN, typically within a city.

• Wireless Local Area Network ...read more

DNS (Domain Name System) is a system that translates domain names to IP addresses to locate resources on the internet.

• DNS works by translating human-readable domain names (like google.com) into IP addresses (like 172.217.3.206).

• Different types of DNS records include A records (for IPv4 addresses), AAAA records (for IPv6 addresses), CNAME records (for aliasing one domain to another), MX records (for mail servers), and TXT records (for arbitrary text data).

• DNS operates through ...read more

Data can be exchanged through various methods such as wired and wireless communication, file transfer protocols, messaging services, and cloud storage.

• Wired communication: Ethernet cables, fiber optic cables

• Wireless communication: Wi-Fi, Bluetooth, cellular networks

• File transfer protocols: FTP, SFTP, TFTP

• Messaging services: Email, instant messaging

• Cloud storage: Dropbox, Google Drive

Check OSPF configuration, network connectivity, router IDs, subnet mismatches, authentication, and hello/dead timers.

• Verify OSPF configuration on both routers

• Check network connectivity between routers

• Ensure router IDs are unique

• Check for subnet mismatches

• Verify authentication settings

• Check hello and dead timers

OSPF priority is a value used to determine the designated router and backup designated router in an OSPF network.

• OSPF priority is a value assigned to each router interface in OSPF.

• The router with the highest priority on a network segment becomes the designated router (DR).

• The router with the second-highest priority becomes the backup designated router (BDR).

• If priorities are tied, the router with the highest router ID becomes the DR.

• Priority values range from 0 to 255, with 0...read more

Explanation of HSRP versions 1 and 2 and OSI model with port numbers and applications at each layer.

• HSRP version 1 uses multicast address 224.0.0.2 and has a default priority of 100.

• HSRP version 2 uses multicast address 224.0.0.102 and has a default priority of 120.

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

• Physical layer uses port numbers 1-1023 and includes devices such as cables and hubs.

• Transport layer uses port...read more

To find the IP address of a website, you can use the 'nslookup' command in the command prompt or use online tools like 'ping' or 'tracert'.

• Use the 'nslookup' command in the command prompt to find the IP address of a website

• Alternatively, you can use online tools like 'ping' or 'tracert' to get the IP address

• For example, in the command prompt, type 'nslookup www.example.com' to get the IP address

A server is a central computer in a network that provides services and resources to other computers.

• A server is a powerful computer that is designed to handle multiple requests from client computers.

• It stores and manages data, applications, and services that can be accessed by other computers in the network.

• Servers can be dedicated to specific tasks such as file storage, email, web hosting, database management, etc.

• They often have high processing power, large storage capacity...read more

Load balancing is the process of distributing network traffic across multiple servers to ensure optimal resource utilization and prevent overload.

• Methods used in load balancing include round-robin, least connections, IP hash, and weighted round-robin.

• The best routing protocol depends on the specific network requirements, but commonly used ones include OSPF, BGP, and EIGRP.

• To create VLANs, configure port channels, set AD values, and assign port numbers, you can use network dev...read more

Troubleshooting steps for routing, switching, and security

• Identify the problem by gathering information and analyzing symptoms

• Verify network connectivity and check for any physical issues

• Check routing tables and configurations for any errors or inconsistencies

• Use network monitoring tools to identify any abnormal traffic patterns

• Review firewall and security settings to ensure proper access control

• Perform packet captures and analyze network traffic for anomalies

• Test and validat...read more

Link state and DV are routing protocols, STP is for loop prevention, BGP is for inter-domain routing.

• Link state protocols (e.g. OSPF) use Dijkstra's algorithm to calculate shortest path.

• Distance vector protocols (e.g. RIP) use Bellman-Ford algorithm and exchange routing tables.

• STP (Spanning Tree Protocol) prevents loops in Ethernet networks by blocking redundant paths.

• BGP (Border Gateway Protocol) is used for inter-domain routing and is based on path vector algorithm.

• Link sta...read more

NAT is used to translate private IP addresses to public IP addresses. PAT is a type of NAT that uses port numbers. Static routing uses manually configured routes. Dynamic routing uses protocols to automatically update routing tables.

• NAT translates private IP addresses to public IP addresses

• PAT is a type of NAT that uses port numbers to map multiple private IP addresses to a single public IP address

• Static routing uses manually configured routes to determine the path of network...read more

OSPF is a routing protocol used to determine the best path for data packets in a network. LSA stands for Link State Advertisement.

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

• LSA (Link State Advertisement) is a packet type used by OSPF to exchange routing information between routers.

• There are different types of LSAs such as Type 1 (Router LSA), Type 2 (Network LSA), Type 3 (Summary LSA), Type 4 ...read more

DNS stands for Domain Name System. It is a system that translates domain names into IP addresses.

• DNS is like a phonebook for the internet

• It helps to locate websites by translating domain names into IP addresses

• DNS servers store information about domain names and their corresponding IP addresses

• DNS queries are sent by web browsers to DNS servers to resolve domain names

• DNS can also be used for other purposes such as email routing and network diagnostics

To provide network for long distance clutter, use technologies like MPLS, SD-WAN, and satellite communication.

• Utilize MPLS (Multiprotocol Label Switching) for efficient routing over long distances

• Implement SD-WAN (Software-Defined Wide Area Network) for centralized control and management of network traffic

• Leverage satellite communication for connectivity in remote or hard-to-reach areas

BGP is a routing protocol used to exchange routing information between different autonomous systems (AS) on the internet.

• BGP uses TCP as its transport protocol

• BGP routers exchange network reachability information with other BGP routers

• BGP selects the best path for each destination based on a set of attributes

• BGP can be used for both IPv4 and IPv6 routing

• BGP is used by internet service providers (ISPs) to connect their networks to each other

Setting up Fex in Nexus involves connecting the Fex to the Nexus switch and configuring it as a fabric extender.

• Connect the Fex to the Nexus switch using a supported connection method such as Ethernet or Fibre Channel.

• Configure the Fex as a fabric extender using the 'fex' command on the Nexus switch.

• Verify the Fex configuration and connectivity to ensure proper operation.

Orphan port in vPC is a port that is not part of any vPC domain.

• An orphan port is a port on a vPC peer switch that is not part of any vPC domain.

• Orphan ports can cause issues such as traffic black-holing or loops.

• To prevent orphan ports, ensure all ports are properly configured and assigned to a vPC domain.

VPC (Virtual Private Cloud) is a virtual network in the cloud that allows users to securely connect their resources.

• VPC provides isolated networking environment in the cloud

• Users can define their own IP address range, subnets, and route tables

• VPC allows creation of public and private subnets

• Network Access Control Lists (ACLs) and Security Groups can be used to control inbound and outbound traffic

• VPC peering enables connection between VPCs in different regions or AWS accounts

Network diagram of zone wise can be created by categorizing network devices and connections based on their respective zones.

• Identify different zones in the network such as DMZ, LAN, WAN, etc.

• Map out network devices and connections within each zone.

• Use network diagram tools like Microsoft Visio or draw.io to create visual representation.

• Label devices and connections with relevant information for clarity.

• Update the diagram regularly to reflect any changes in the network infrast...read more

vPC (Virtual Port Channel) allows links that are physically connected to two different Nexus switches to appear as a single port channel.

• vPC allows for redundancy and load balancing by enabling a device to connect to two separate Nexus switches simultaneously.

• It eliminates Spanning Tree Protocol (STP) blocked ports by allowing both links to be active.

• vPC peer-link is used for synchronization between the two Nexus switches.

• vPC member ports are configured with the same port cha...read more

Yes, I am familiar with fiber splicing and crimping.

• I have experience with both mechanical and fusion splicing techniques.

• I am proficient in using fiber optic cleavers, fusion splicers, and OTDRs.

• I am also skilled in crimping fiber optic connectors.

• I have worked with various types of fiber optic cables, including single-mode and multi-mode.

• I am familiar with industry standards and best practices for fiber optic splicing and crimping.

BGP is used for routing between autonomous systems. LP and weight are used for path selection. MED is used for path advertisement.

• BGP is used for inter-domain routing between autonomous systems.

• LP (Local Preference) is used to select the preferred path among multiple paths within the same AS.

• Weight is a Cisco proprietary parameter used to select the preferred path among multiple paths within the same AS.

• MED (Multi-Exit Discriminator) is used to influence the path selection in...read more

I would prioritize the ticket based on severity, communicate with the customer for more information, troubleshoot the issue, and provide timely updates.

• Prioritize the ticket based on severity level

• Communicate with the customer for more information

• Troubleshoot the issue using relevant tools and resources

• Provide timely updates to the customer on the progress

Forwarding, delegation, and stub zones are all methods of DNS resolution.

• Forwarding involves sending DNS queries to another DNS server for resolution.

• Delegation involves assigning responsibility for a subdomain to another DNS server.

• Stub zones are a copy of a zone's NS records used to reduce DNS query traffic.

• All three methods can improve DNS performance and reliability.

• Forwarding and delegation can be configured at the DNS server level.

• Stub zones are configured on the DNS cl...read more

An IP address is a unique numerical label assigned to each device connected to a computer network.

• IP address stands for Internet Protocol address.

• It is used to identify and locate devices on a network.

• There are two types of IP addresses: IPv4 and IPv6.

• IPv4 addresses are written in the format of four sets of numbers separated by periods (e.g., 192.168.0.1).

• IPv6 addresses are written in the format of eight sets of hexadecimal numbers separated by colons (e.g., 2001:0db8:85a3:00...read more

BGP attributes are used to determine the best path for routing. Path selection process involves comparing attributes like AS path, local preference, etc.

• BGP attributes include AS path, local preference, MED, origin, etc.

• Path selection process involves comparing attributes in a predetermined order to determine the best path.

• AS path attribute is used to prevent routing loops and determine the shortest path to a destination.

• Local preference attribute is used to influence outboun...read more

Network cabling refers to the physical cables and wires used to connect devices in a network.

• Network cabling can be made of copper or fiber optic materials.

• Cables can be run through walls, ceilings, and floors to connect devices in different rooms or areas.

• Different types of cables are used for different purposes, such as Ethernet cables for internet connections and coaxial cables for cable TV.

• Proper installation and maintenance of network cabling is important for ensuring re...read more

Network topology refers to the physical or logical layout of a network.

• Physical topology: Bus, Star, Ring, Mesh, Hybrid

• Logical topology: Ethernet, Token Ring, FDDI, ATM

• Network topology determines how devices are connected and how data flows through the network

• It affects network performance, scalability, and security

STP stands for Spanning Tree Protocol. It is used to prevent loops in a network and ensure redundancy.

• STP is a layer 2 protocol used in Ethernet networks

• It prevents loops by blocking redundant paths

• It selects a root bridge and calculates the shortest path to it

• It can be configured with different priorities and timers

• Examples of STP variants include RSTP and MSTP

Seeking new challenges and opportunities for growth in a different field.

• Desire to expand skill set and knowledge in a new industry

• Interest in tackling different technical challenges

• Seeking a fresh start and new experiences

• Opportunity for career advancement and personal development

BGP stands for Border Gateway Protocol, used for routing and exchanging routing information between different autonomous systems.

• BGP is used to connect different autonomous systems on the internet.

• It is a path vector protocol that helps in determining the best path for data to travel.

• BGP uses TCP port 179 for communication.

• It is commonly used by Internet Service Providers (ISPs) and large organizations to manage routing between networks.

BGP stands for Border Gateway Protocol, a routing protocol used to exchange routing information between different networks. AD value refers to Administrative Distance, a metric used to determine the trustworthiness of routing information.

• BGP is used to exchange routing information between different autonomous systems

• AD value is a metric used to determine the trustworthiness of routing information

• Lower AD value indicates higher trustworthiness of the route

• For example, BGP is c...read more

MPLS architecture is a network protocol that directs data packets along predetermined paths through a network. BGP is a routing protocol used to exchange routing information between different networks.

• MPLS (Multiprotocol Label Switching) is a protocol used to speed up and shape traffic flows across high-performance networks.

• MPLS architecture involves routers using labels to make forwarding decisions, improving network performance and efficiency.

• BGP (Border Gateway Protocol) i...read more

Yes, I have worked on configuring and managing firewalls in various network environments.

• Configured firewall rules to control traffic flow

• Managed firewall policies to ensure network security

• Troubleshooted firewall issues and implemented solutions

• Worked with different firewall vendors such as Cisco, Palo Alto, and Fortinet

VxLAN stands for Virtual Extensible LAN, a technology used to extend Layer 2 networks over Layer 3 networks.

• VxLAN encapsulates Layer 2 Ethernet frames within Layer 3 UDP packets for transmission over IP networks.

• It uses a 24-bit identifier called the VxLAN Network Identifier (VNI) to distinguish between different virtual networks.

• VxLAN allows for up to 16 million virtual networks to coexist in the same administrative domain.

• It helps in creating large-scale multi-tenant cloud ...read more

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

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.

GPON network is a passive optical network that uses fiber-optic cables to transmit data.

• GPON network uses a single fiber-optic cable to transmit data to multiple users

• It uses a point-to-multipoint architecture

• GPON network has an Optical Line Terminal (OLT) at the service provider's end and an Optical Network Unit (ONU) at the user's end

• GPON network uses different wavelengths of light to transmit data upstream and downstream

• GPON network is a cost-effective solution for high-sp...read more

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