800+ Network Engineer Interview Questions and Answers

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.

Traditional Mac learning is static while conversation Mac learning is dynamic.

• Traditional Mac learning involves manually configuring MAC addresses in the switch's MAC address table.

• Conversation Mac learning involves the switch dynamically learning MAC addresses based on the source address of incoming frames.

• Traditional Mac learning is more prone to errors and requires more manual intervention.

• Conversation Mac learning is more efficient and reduces the risk of errors.

• Conversat...read more

Avaya has been significantly affected by the recession.

• Avaya has experienced a decline in revenue and profitability due to the recession.

• The recession has led to reduced spending on communication and networking infrastructure, impacting Avaya's sales.

• Avaya may have faced challenges in securing new contracts and retaining existing customers during the recession.

• The company may have implemented cost-cutting measures such as layoffs or reduced investments in research and develop...read more

To create firewall rules on a Checkpoint device, follow these steps:

• Log in to the Checkpoint device using SmartConsole

• Navigate to the Firewall tab and select the Access Rules section

• Click on the Add Rule button and specify the source, destination, and service for the rule

• Set the action for the rule (allow, drop, reject, etc.)

• Click on Install Policy to apply the new rule to the device

Wireshark is a network protocol analyzer used for troubleshooting network issues and analyzing network traffic.

• Wireshark captures and displays network packets in real-time.

• It can be used to identify network issues, such as latency or packet loss.

• Wireshark can also be used to analyze network traffic for security purposes, such as detecting malicious activity or unauthorized access.

• To use Wireshark, you need to select the network interface to capture traffic from, start the cap...read more

4G technical network operation, planning and design

• Understanding of LTE/4G network architecture and protocols

• Knowledge of radio frequency planning and optimization

• Experience in designing and implementing 4G networks

• Familiarity with network performance monitoring and troubleshooting

• Ability to work with vendors and stakeholders to ensure network reliability and scalability

VPN is a secure way to connect to a private network over the internet. Private IP ranges are used to assign IP addresses within a network.

• VPN stands for Virtual Private Network

• It allows users to securely access a private network over the internet

• VPN encrypts the data transmitted over the network to ensure security

• Private IP ranges are used to assign IP addresses within a network

• There are three classes of private IP ranges: Class A (10.0.0.0 – 10.255.255.255), Class B (172.16....read more

A port number is a communication endpoint in networking. Public ports are accessible from the internet, while private ports are only accessible within a local network.

• Port numbers range from 0 to 65535 and are used to identify different services or processes on a network.

• Public ports are exposed to the internet and allow external communication, like port 80 for HTTP.

• Private ports are used for internal communication within a network, like port 22 for SSH.

• Port numbers help dire...read more

DHCP is a network protocol that dynamically assigns IP addresses to devices on a network. APIPA is a feature in Windows that assigns a default IP address when DHCP fails. EIGRP is a routing protocol used in networking.

• DHCP stands for Dynamic Host Configuration Protocol

• DHCP server assigns IP addresses to devices on a network dynamically

• APIPA (Automatic Private IP Addressing) assigns a default IP address in the range of 169.254.0.1 to 169.254.255.254 when DHCP server is not ava...read more

I prioritize network support requests based on urgency, impact, and SLA requirements to ensure efficient resolution.

• Assess urgency: Identify critical issues affecting business operations, like a network outage, and address them first.

• Evaluate impact: Determine how many users or systems are affected; prioritize requests that impact a larger group.

• Check SLA requirements: Follow Service Level Agreements to ensure compliance and prioritize requests based on their urgency.

• Communic...read more

Explanation of STP, HSRP, VLAN, RSTP, BPDU guard and BPDU filter in network switching.

• STP (Spanning Tree Protocol) is used to prevent loops in a network by blocking redundant paths.

• HSRP (Hot Standby Router Protocol) provides redundancy for IP networks by allowing multiple routers to share a virtual IP address.

• VLAN (Virtual Local Area Network) is a logical grouping of devices on a network, allowing for better network management and security.

• RSTP (Rapid Spanning Tree Protocol) ...read more

I have worked on designing, implementing, and troubleshooting wireless networks for various organizations.

• Designed wireless network infrastructure to meet specific requirements

• Implemented wireless access points and controllers for seamless connectivity

• Troubleshooted network issues to ensure optimal performance

• Performed site surveys to determine optimal placement of access points

OSPF is a routing protocol used to exchange routing information within a single autonomous system. OSI model is a conceptual model used to describe network communication.

• OSPF stands for Open Shortest Path First

• It is a link-state routing protocol

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

• OSPF is used within a single autonomous system

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

• It is a conceptual model ...read more

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

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

• It ensures that there is only one active path between any two network devices.

• STP works by creating a tree-like structure of the network, with one root bridge and multiple branches.

• If a link fails, STP will automatically reroute traffic to an alternate path.

• Examples of STP variants include RSTP, MSTP, an...read more

VLANs are used to logically separate network traffic and improve network performance and security.

• VLANs allow for better network management and organization by grouping devices based on their function or location.

• They also reduce network congestion by limiting broadcast traffic to devices within the same VLAN.

• VLANs can improve network security by isolating sensitive data or devices from the rest of the network.

• For example, a finance department may have their own VLAN to keep ...read more

I am available for 24/7 support and weekend availability as required.

• I am willing to work flexible hours to provide support whenever needed

• I understand the importance of maintaining network uptime and am committed to being available when necessary

• I have experience working weekends and off-hours in previous roles, ensuring smooth operations during critical times

To troubleshoot a switch in ROMMON mode after a reboot, follow these steps.

• Check the configuration register value to ensure it is correct

• Verify the boot image and configuration file are present and accessible

• Attempt to boot the switch manually using the boot command

• If necessary, reload the switch with a valid IOS image from a TFTP server

Answering questions related to crimping, UTP fiber, VLANs, and the difference between hub and switch for a Network Engineer position.

• Crimping RJ45 connectors onto UTP cables is a common task for network engineers. Advantages include ease of installation and cost-effectiveness. Disadvantages include susceptibility to interference and limited distance.

• UTP fiber cables offer higher bandwidth and longer distances than UTP cables. Advantages include immunity to electromagnetic int...read more

ACLs are used to control traffic flow by filtering packets based on defined criteria. They can be implemented on line vty to secure management traffic.

• ACLs can be created to permit or deny traffic based on source/destination IP address, port numbers, or protocols

• To secure management traffic on line vty, an ACL can be applied to restrict access to specific IP addresses or ranges

• For example, to allow only a specific IP address to access the management interface, an ACL can be c...read more

To manage all network issues in critical condition, prioritize tasks, troubleshoot systematically, communicate effectively, and have backup plans.

• Prioritize tasks based on impact and urgency

• Troubleshoot systematically by isolating the issue, gathering relevant data, and testing solutions

• Communicate effectively with team members, stakeholders, and vendors to coordinate efforts

• Have backup plans in place for critical systems and data

• Regularly update documentation and network dia...read more

Answers to various networking questions related to VLANs, BGP, SSH, Telnet, and OSPF.

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

• EBGP (External BGP) is used between different AS (Autonomous Systems), while IBGP (Internal BGP) is used within the same AS.

• BGP uses the 'AD value' (Administrative Distance) to determine the best path to a destination.

• SSH (Secure Shell) uses port number 22 for secure remote access.

• Telnet uses port number 23 for unencrypted re...read more

NATting is a process of modifying network address information in packet headers, LSA types include Type 1, Type 2, Type 3, Type 4, Type 5, and Type 7, IPsec tunnel is a secure communication channel established between two devices.

• NATting stands for Network Address Translation, used to modify network address information in packet headers

• Types of LSA (Link State Advertisement) include Type 1 (Router LSA), Type 2 (Network LSA), Type 3 (Summary LSA), Type 4 (ASBR Summary LSA), Ty...read more

Ping and Traceroute are network diagnostic tools used to test connectivity and identify network issues.

• Ping sends a small packet of data to a destination IP address and waits for a response. It measures the time it takes for the packet to travel to the destination and back.

• Traceroute sends packets with increasing TTL values to the destination, and each router along the path sends back an ICMP message indicating its presence. This helps to identify the path taken by the packet...read more

To configure username and password on a router, follow these steps:

• Access the router's configuration page through a web browser

• Navigate to the security settings section

• Create a new username and password

• Save the changes and log out of the configuration page

• Test the new login credentials to ensure they work

A network is a collection of interconnected devices that can communicate and share resources. Network cables are color-coded to identify their purpose and functionality.

• A network is a system of devices, such as computers, servers, routers, and switches, connected together to facilitate communication and resource sharing.

• Network cables are used to connect these devices and transmit data between them.

• Color coding of network cables helps in identifying their purpose and function...read more

I have worked on a variety of technologies as a Network Engineer.

• Cisco networking equipment

• Routing and switching protocols (e.g. OSPF, BGP)

• Firewalls and security appliances (e.g. Cisco ASA, Palo Alto)

• Network monitoring and management tools (e.g. SolarWinds, Wireshark)

• Virtualization technologies (e.g. VMware, Hyper-V)

• Load balancers (e.g. F5, Citrix NetScaler)

• Wireless networking (e.g. Cisco Meraki, Aruba)

• Network troubleshooting and performance optimization

TCP/IP is a protocol used for communication between devices on a network. IPV4 and IPV6 are two versions of the protocol.

• TCP/IP is a suite of protocols that governs communication between devices on a network

• IPV4 uses 32-bit addresses and can support up to 4.3 billion unique addresses

• IPV6 uses 128-bit addresses and can support up to 340 undecillion unique addresses

• TCP is responsible for establishing and maintaining a connection between devices

• IP is responsible for routing data...read more

Yes, I have plans to pursue CCNA certification in the near future.

• I have already started studying for the CCNA exam

• I believe that obtaining the CCNA certification will enhance my skills and knowledge in network engineering

• I plan to take the exam within the next 6 months

OTN frame structure includes FEC for error correction and DWDM components for multiplexing.

• OTN frame structure consists of a header and payload.

• FEC (Forward Error Correction) is used for error correction in OTN.

• DWDM (Dense Wavelength Division Multiplexing) components are used for multiplexing in OTN.

• OTN frame structure is standardized by ITU-T G.709.

• OTN is widely used in long-haul optical networks.

HSRP stands for Hot Standby Router Protocol. It is a Cisco proprietary protocol used to provide redundancy for IP networks.

• HSRP is used to create a virtual IP address that can be shared by multiple routers in a network.

• It allows for automatic failover in case the primary router fails.

• HSRP routers elect an active router and standby routers, with the active router handling traffic while the standby routers are ready to take over if needed.

• It uses a virtual MAC address and a vir...read more

MPLS (Multiprotocol Label Switching) is a protocol used in high-performance telecommunications networks to direct data packets along predefined paths.

• MPLS is used to improve network performance by efficiently routing data packets based on labels instead of IP addresses.

• It is commonly used in scenarios where quality of service (QoS) and traffic engineering are important, such as in large enterprise networks or service provider networks.

• MPLS can be used to create virtual privat...read more

When the browser first visits facebook.com, it goes through multiple protocols in different layers.

• The browser first resolves the domain name using DNS (Domain Name System).

• Then, it establishes a TCP (Transmission Control Protocol) connection with the server.

• Next, it performs an SSL/TLS handshake to establish a secure connection.

• After that, the browser sends an HTTP (Hypertext Transfer Protocol) request to the server.

• The server processes the request and sends back an HTTP res...read more

DHCP Dora process assigns IP addresses to devices. DNS resolves domain names to IP addresses.

• DHCP Dora process involves four steps: Discover, Offer, Request, and Acknowledge.

• DHCPv6 is the IPv6 version of DHCP.

• DNS works by translating domain names into IP addresses.

• DNS uses a hierarchical system of domain names and servers.

• DNS queries can be recursive or iterative.

• DNS caching helps to reduce network traffic and improve performance.

Switches connect devices within a network, while routers connect different networks and enable communication between them.

• Switches operate at the data link layer of the OSI model and use MAC addresses to forward data within a network.

• Routers operate at the network layer of the OSI model and use IP addresses to route data between different networks.

• Switches create multiple collision domains, while routers create multiple broadcast domains.

• Switches are used in LANs to connect d...read more

To avoid loop in IBGP and EBGP, use route reflectors or confederations.

• Use route reflectors to avoid full mesh IBGP and confederations to avoid full mesh EBGP.

• Configure the router to not advertise the same prefix received from one neighbor to another neighbor.

• Use AS path prepending to influence the path selection in EBGP.

• Configure loopback interfaces on routers to avoid the use of physical interfaces in BGP updates.

• Use BGP TTL security feature to prevent BGP packets from loop...read more

BGP attributes are characteristics used to determine the best path for routing traffic between networks.

• BGP attributes include: AS Path, Next Hop, Local Preference, Multi-Exit Discriminator (MED), Weight, and Origin.

• AS Path identifies the sequence of autonomous systems that the route has passed through.

• Next Hop identifies the IP address of the next router in the path.

• Local Preference is used to indicate the preferred path for outbound traffic.

• MED is used to determine the pref...read more

STP is a protocol used to prevent network loops. DP and RP are elected based on their bridge priority and MAC address.

• STP stands for Spanning Tree Protocol

• It prevents network loops by blocking redundant paths

• Designated Port (DP) is the port that forwards traffic on a segment

• Root Port (RP) is the port that has the shortest path to the root bridge

• DP and RP are elected based on their bridge priority and MAC address

• The bridge with the lowest bridge ID becomes the root bridge

• STP r...read more

No, RT and RD are required for MPLS VPN implementation.

• RT (Route Target) and RD (Route Distinguisher) are used to uniquely identify VPN routes.

• Without RT and RD, MPLS VPN cannot differentiate between different VPN routes.

• RT and RD are used to import and export VPN routes between different VPNs.

• RT and RD are also used for route filtering and traffic engineering.

• Therefore, RT and RD are essential for MPLS VPN implementation.

I operate various network monitoring and troubleshooting tools.

• I am proficient in using Wireshark for packet analysis

• I have experience with Cisco Prime Infrastructure for network management

• I am familiar with SolarWinds for network monitoring

• I have used PingPlotter for network troubleshooting

• I am comfortable with CLI tools like ping, traceroute, and netstat

The OSI model has 7 layers that define how data is transmitted over a network.

• Layer 1: Physical - deals with the physical connection of devices

• Layer 2: Data Link - responsible for error-free transfer of data between devices

• Layer 3: Network - handles routing of data between different networks

• Layer 4: Transport - ensures reliable delivery of data between applications

• Layer 5: Session - establishes and manages connections between applications

• Layer 6: Presentation - translates dat...read more

VLAN stands for Virtual Local Area Network. It is a logical grouping of devices on a network based on function, department or application.

• VLANs allow network administrators to segment a network into smaller, more manageable groups.

• Devices in a VLAN can communicate with each other as if they were on the same physical network, even if they are physically located on different switches.

• VLANs can improve network security by isolating sensitive data and restricting access to certai...read more

Active DAS uses signal boosters to amplify and distribute wireless signals, while Passive DAS uses passive components like cables and antennas.

• Active DAS requires power to operate, while Passive DAS does not.

• Active DAS can cover larger areas and support more users, while Passive DAS is better suited for smaller areas.

• Active DAS is more expensive to install and maintain than Passive DAS.

• Examples of Active DAS include WilsonPro 1050 and SureCall Fusion5s, while examples of Pass...read more

Cascade and master slave switching are methods used in networking to connect multiple switches together for improved performance and redundancy.

• Cascade switching involves connecting multiple switches in a linear fashion, where each switch is connected to the previous one.

• Master-slave switching involves designating one switch as the master, which controls the operation of the slave switches in the network.

• Stack switching involves connecting multiple switches together to form a...read more

Straight through cables are used to connect different types of devices, while crossover cables are used to connect similar devices.

• Straight through cables have the same wiring at both ends, while crossover cables have the wiring reversed at one end.

• Straight through cables are commonly used to connect a computer to a switch or router, while crossover cables are used to connect two computers or two switches directly.

• Examples of straight through cables include connecting a compu...read more

DNS issue can be resolved by checking DNS server settings, clearing cache, flushing DNS, and checking network connectivity.

• Check DNS server settings and ensure they are correct

• Clear DNS cache on the client machine

• Flush DNS resolver cache on the DNS server

• Check network connectivity and ensure there are no firewall or routing issues

• Use tools like nslookup or dig to troubleshoot DNS issues

GPON technology is a fiber optic communication technology that enables high-speed data transmission over long distances.

• GPON stands for Gigabit Passive Optical Network.

• It uses a single optical fiber to deliver data, voice, and video services.

• GPON technology is widely used in Fiber-to-the-Home (FTTH) and Fiber-to-the-Building (FTTB) networks.

• FTTH refers to the deployment of optical fiber directly to individual homes, providing high-speed internet access.

• FTTB refers to the depl...read more