10+ Interview Questions and Answers

Phase 1 is for establishing a secure channel and Phase 2 is for negotiating IPSec SAs.

• IKEv1 is a protocol used for VPN tunneling

• Phase 1 negotiates the parameters for the secure channel

• Phase 2 negotiates the IPSec SAs for data transmission

• Phase 1 uses Diffie-Hellman for key exchange

• Phase 2 uses either AH or ESP for data encryption and authentication

TCP flags are control bits used in TCP to indicate the status of a connection.

• TCP flags are 6 bits in the TCP header.

• They are used to indicate the status of a connection, such as whether it is being opened, closed, or reset.

• Some common TCP flags include SYN, ACK, FIN, RST, and URG.

• SYN is used to initiate a connection, ACK is used to acknowledge receipt of data, FIN is used to terminate a connection, RST is used to reset a connection, and URG is used to indicate urgent data.

• TC...read more

ARP is a protocol used to map an IP address to a MAC address. It detects different networks by comparing the IP address and subnet mask.

• ARP stands for Address Resolution Protocol

• It maps an IP address to a MAC address

• It works by broadcasting an ARP request to all devices on the network

• The device with the matching IP address responds with its MAC address

• If the destination device is in a different network, ARP compares the IP address and subnet mask to determine this

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

NAT-T is a protocol used to encapsulate and encrypt IPsec traffic when NAT is used in the network.

• NAT-T stands for Network Address Translation - Traversal

• It allows IPsec traffic to pass through NAT devices

• It encapsulates and encrypts IPsec traffic in UDP packets

• It uses port 4500 by default

• Example: A remote worker using a VPN to connect to their company's network from a hotel room with a NAT router

SSL handshake is a process of establishing a secure connection between a client and a server.

• Client sends a request to the server to initiate the SSL handshake

• Server responds with its SSL certificate

• Client verifies the certificate and generates a symmetric key

• Client sends a message encrypted with the symmetric key to the server

• Server decrypts the message and sends a confirmation to the client

• The SSL handshake is complete and secure communication can begin

SSL Inspection is a process of intercepting and decrypting SSL/TLS traffic to inspect it for security purposes.

• SSL Inspection intercepts SSL/TLS traffic and decrypts it

• It allows inspection of encrypted traffic for security threats

• It requires a trusted root certificate to be installed on the device

• It can cause issues with end-to-end encryption and privacy concerns

Trojan is a type of malware disguised as legitimate software, while worm is a self-replicating malware that spreads through networks.

• Trojan is a non-self-replicating malware that requires user interaction to spread.

• Worm is a self-replicating malware that spreads through networks without user interaction.

• Trojans often appear as legitimate software or files to trick users into downloading and executing them.

• Worms exploit vulnerabilities in network protocols to spread rapidly an...read more

Abstract class is a class that cannot be instantiated and can have both abstract and non-abstract methods. Interface is a collection of abstract methods.

• Abstract class can have constructors while interface cannot

• A class can implement multiple interfaces but can only inherit from one abstract class

• Abstract class can have instance variables while interface cannot

• Abstract class is used when we want to provide a common base implementation to derived classes while interface is use...read more

VPN stands for Virtual Private Network, a secure connection that allows users to access the internet privately and securely.

• VPN encrypts data to ensure privacy and security

• It masks the user's IP address to protect their identity

• VPN can be used to access region-restricted websites or services

• Common VPN protocols include OpenVPN, L2TP/IPsec, and IKEv2

EDR stands for Endpoint Detection and Response, a cybersecurity technology that continuously monitors and responds to potential threats on endpoints.

• EDR solutions collect and analyze endpoint data to detect suspicious activities and potential threats.

• They provide real-time visibility into endpoint activities and allow for quick response to incidents.

• Measures of EDR include threat detection, incident response, endpoint visibility, and continuous monitoring.

• Examples of EDR solu...read more

Inorder traversal is a way of visiting all nodes in a binary tree by visiting left subtree, then root, then right subtree.

• Start at the root node

• Traverse the left subtree recursively

• Visit the root node

• Traverse the right subtree recursively

• Repeat until all nodes are visited

Git commands are used to manage version control of code. There are various types of Git commands.

• Basic commands: add, commit, push, pull, clone

• Branching commands: branch, checkout, merge, rebase

• Advanced commands: stash, cherry-pick, reset, revert

• Query commands: log, diff, blame, show

LRU cache is a data structure that stores the most recently used items and discards the least recently used items.

• Use a doubly linked list to keep track of the order of items in the cache

• Use a hash table to store the key-value pairs for fast access

• When a new item is added, check if the cache is full and remove the least recently used item if necessary

Penetration testing involves simulating various types of cyber attacks to identify vulnerabilities in a system.

• Types of attacks include phishing, malware, denial of service, and SQL injection.

• Penetration testing helps organizations identify weaknesses in their security measures.

• Examples of penetration testing tools include Metasploit, Nmap, and Burp Suite.