100+ Network Security Engineer Interview Questions and Answers

Port 443 is used for secure HTTP (HTTPS) communication over the internet.

• Port 443 is the default port for HTTPS traffic, which encrypts data using SSL/TLS protocols.

• It is commonly used for secure communication between web browsers and servers.

• HTTPS ensures that data transmitted over the internet is encrypted and secure.

• Many websites, such as online banking and e-commerce sites, use port 443 to protect sensitive information.

SSL persistence is a feature in F5 that allows a client to maintain a secure connection with the same server during a session.

• SSL persistence ensures that a client's SSL session is maintained with the same server throughout the session.

• This feature is useful in scenarios where multiple servers are used to handle client requests.

• SSL persistence can be configured based on SSL session ID, SSL session ticket, or SSL session match across multiple requests.

• For example, if a client ...read more

Firewalls protect networks by controlling incoming and outgoing traffic based on predetermined security rules.

• Acts as a barrier between trusted and untrusted networks.

• Monitors and filters traffic based on security policies.

• Can be hardware-based (like a dedicated appliance) or software-based (like an application on a server).

• Examples include packet filtering, stateful inspection, and application-layer filtering.

• Can prevent unauthorized access and mitigate threats like malware ...read more

Upgrading OS in distributed mode requires careful planning and execution.

• Ensure compatibility of new OS with existing hardware and software

• Create a backup of all important data before starting the upgrade process

• Test the upgrade process in a non-production environment first

• Schedule the upgrade during a maintenance window to minimize disruption

• Monitor the upgrade process closely and have a rollback plan in case of issues

DNS infrastructure is a system that translates domain names into IP addresses to enable communication between devices on a network.

• DNS servers store records of domain names and their corresponding IP addresses.

• DNS resolution can be recursive or iterative.

• DNS cache is used to speed up the resolution process.

• DNSSEC is used to secure DNS infrastructure.

• DNS load balancing can be used to distribute traffic across multiple servers.

• DNS hijacking is a type of attack that redirects DN...read more

The VLANs used depend on the network architecture and requirements.

• VLANs are used to logically separate network traffic.

• They can be used to improve security and network performance.

• Common VLANs include management, voice, and data VLANs.

• The VLANs used depend on the network architecture and requirements.

• VLAN tagging is used to identify VLAN traffic on a network.

• VLANs can be configured on switches, routers, and firewalls.

Application override is a feature in network security that allows certain applications to bypass security policies.

• Application override allows specific applications to bypass firewall rules or other security measures.

• It is typically used for critical applications that may be blocked by default security settings.

• Administrators can configure application override rules to allow certain traffic to pass through the network without inspection.

• This feature can be useful for ensuring...read more

VLAN stands for Virtual Local Area Network. It is a logical grouping of network devices that share the same broadcast domain.

• VLANs are used to improve network performance, security, and management.

• They allow network administrators to segment a large network into smaller, more manageable subnetworks.

• Each VLAN has its own broadcast domain, which reduces network congestion and improves performance.

• VLANs can also be used to enhance network security by isolating sensitive data and...read more

BGP stands for Border Gateway Protocol, a routing protocol used to exchange routing information between different networks.

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

• It is a path-vector protocol that selects the best path for data to travel based on various attributes.

• BGP is used by internet service providers (ISPs) to exchange routing information with each other.

• It is a complex protocol that requires careful configuration to ensure proper routin...read more

NAT stands for Network Address Translation. It is a technique used to map a public IP address to a private IP address.

• NAT is used to conserve public IP addresses.

• It allows multiple devices to share a single public IP address.

• NAT can be implemented using hardware or software.

• There are three types of NAT: Static NAT, Dynamic NAT, and Port Address Translation (PAT).

I will handle customers by providing timely and effective communication, understanding their needs, and offering solutions to their problems.

• Listen actively to understand customer concerns

• Communicate clearly and effectively to address customer needs

• Offer solutions and follow up to ensure customer satisfaction

TCP is connection-oriented and reliable while UDP is connectionless and unreliable.

• TCP establishes a connection before data transfer while UDP does not.

• TCP ensures data delivery and order while UDP does not guarantee either.

• TCP is slower but more secure while UDP is faster but less secure.

• TCP is used for applications like email, file transfer, and web browsing while UDP is used for applications like video streaming, online gaming, and DNS.

• TCP uses flow control and congestion ...read more

IKEv2 is more secure and efficient than IKEv1 for IPsec VPN.

• IKEv2 supports more secure encryption algorithms and has better resistance to attacks.

• IKEv2 has faster negotiation and rekeying times, improving performance.

• IKEv2 allows for more flexibility in terms of authentication methods.

• IKEv1 is still widely used and supported, but IKEv2 is recommended for new deployments.

• Both IKEv1 and IKEv2 are used to establish a secure connection between two devices over the internet.

Stateful means the system or device keeps track of the state of active connections and can differentiate between different connections.

• Stateful devices maintain information about the state of active connections

• They can differentiate between different connections based on various parameters

• Stateful firewalls keep track of the state of network connections to make decisions on allowing or blocking traffic

To troubleshoot internet issue, check network connectivity, DNS settings, firewall, and router configuration.

• Check if other devices are able to connect to the internet

• Verify DNS settings and try using a different DNS server

• Check firewall settings and ensure that the required ports are open

• Check router configuration and restart if necessary

The phases of a VPN include initiation, negotiation, data transfer, and termination.

• Initiation phase involves establishing a connection between the client and server.

• Negotiation phase involves agreeing on encryption algorithms and keys.

• Data transfer phase is when actual data is transmitted securely.

• Termination phase involves closing the connection.

• Examples: IKEv2 VPN protocol follows these phases.

IPSEC Tunnel Ike is a secure tunneling protocol used to establish a secure connection between two devices over the internet.

• IPSEC Tunnel Ike is used to encrypt and authenticate traffic between two devices

• It uses Internet Key Exchange (IKE) protocol to establish a secure connection

• It provides confidentiality, integrity, and authenticity of data transmitted over the internet

• IPSEC Tunnel Ike is commonly used in VPNs to provide secure remote access to corporate networks

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

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

• It enables the sharing of data, information, and resources such as printers and storage devices.

• Networks can be wired or wireless, local (LAN) or wide area (WAN).

• Examples of networks include the internet, corporate intranets, and home networks.

To troubleshoot IPsec vpns, check configuration, logs, and network connectivity.

• Check if the configuration is correct and matches on both ends

• Check the logs for any error messages or warnings

• Verify network connectivity between the two endpoints

• Check for any firewall or NAT issues

• Ensure that the correct encryption and authentication algorithms are being used

• Check for any MTU issues

• Verify that the VPN tunnel is up and running

• Use packet capture tools to analyze traffic

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

• STP elects a root bridge to serve as the central point in the network

• Each switch determines the best path to the root bridge based on the lowest path cost

• Ports on switches are designated as root ports, designated ports, or blocking ports to create a loop-free topology

SSL handshake is a process where a client and server establish a secure connection by exchanging encryption keys and verifying identities.

• Client sends a hello message to server with supported encryption algorithms

• Server responds with its own hello message, including its certificate

• Client verifies server's certificate and generates a pre-master secret

• Both client and server use the pre-master secret to generate a unique session key for encryption

• Encrypted communication begins u...read more

Common network protocols and their associated port numbers for TCP, UDP, FTP, HTTPS, and HTTP.

• TCP (Transmission Control Protocol) is used for reliable communication, typically on port 80 for HTTP.

• UDP (User Datagram Protocol) is used for faster, connectionless communication, often on port 53 for DNS.

• FTP (File Transfer Protocol) operates on TCP port 21 for control and port 20 for data transfer.

• HTTPS (Hypertext Transfer Protocol Secure) uses TCP port 443 for secure web traffic.

• H...read more

A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules.

• Acts as a barrier between a trusted internal network and untrusted external network

• Can be hardware-based or software-based

• Filters traffic based on IP addresses, ports, protocols, and other criteria

• Examples include Cisco ASA, Palo Alto Networks, and pfSense

An engineer is a professional who applies scientific and mathematical principles to design, develop, and maintain systems or structures.

• Engineers use their knowledge and skills to solve complex problems and improve existing systems.

• They work in various fields such as civil, mechanical, electrical, and software engineering.

• Network Security Engineers specialize in securing computer networks and protecting them from unauthorized access or attacks.

• They design and implement securi...read more

Security refers to the measures taken to protect systems, networks, and data from unauthorized access, use, disclosure, disruption, modification, or destruction.

• Security involves implementing various controls and safeguards to prevent unauthorized access to sensitive information.

• It includes measures such as encryption, firewalls, access controls, and intrusion detection systems.

• Security also involves regular monitoring, vulnerability assessments, and incident response to iden...read more

VPN stands for Virtual Private Network, a secure connection between two or more devices over the internet. Protocol is a set of rules for communication between devices.

• VPN allows users to securely access a private network and share data remotely

• Protocols define how data is formatted, transmitted, and received

• Examples of VPN protocols include OpenVPN, L2TP/IPsec, and IKEv2

• Examples of communication protocols include TCP, UDP, HTTP, and FTP

VLAN stands for Virtual Local Area Network. It is a network technology that allows for segmentation of a single physical network into multiple virtual networks.

• VLANs help improve network security by isolating traffic between different groups of users.

• Types of VLANs include: port-based VLANs, MAC address-based VLANs, protocol-based VLANs, and subnet-based VLANs.

• For example, a company may have separate VLANs for finance, marketing, and IT departments to restrict access to sensi...read more