Best 50+ CCNA Interview Questions & Answers in 2020 [95% SUCCESS]
CCNA Interview Questions and Answers

Best 50+ CCNA Interview Questions & Answers [95% SUCCESS]

Last updated on 16th Jun 2020, Blog, Interview Questions

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In order to be qualified for the employment linked with the CCNA, both professionals and students must update their knowledge and abilities with the latest features. Experts must be familiar with all of the CCNA technologies’ components due to the hundreds of open positions for CCNA developers. For the students to have a thorough understanding of the subject and to have greater work options in the future, this is required. One study indicates that the majority of organizations and companies have switched to the CCNA. For those with experience in the relevant technologies, it is currently impossible to forecast how significant the future will be.

CCNA will therefore assist you in achieving the pinnacle of your job if you want to enhance your profile and secure your future. In addition to this, you would have a lot of opportunities as a new student. The top 100 CCNA interview questions and their responses are shown below.

1. What is a network?

Ans:

A network is a group of connected objects, such computers,servers, switches, and routers, that are linked together to enable communication and resource sharing. Networks can be local (LAN), spanning across buildings (MAN), or covering vast geographical distances (WAN or the internet). They rely on various protocols and technologies to facilitate data exchange.

2.  What is a MAC address?

Ans:

Each network interface card (NIC) or network adapter has a specific identifier known as a MAC (Media Access Control) address, often known as a hardware or physical address. To guarantee that data frames are delivered to the right device on a local network segment, this address is employed at the data link layer of the OSI model.

3. Explain the OSI model.

Ans:

 A conceptual framework known as the OSI (Open Systems Interconnection) model standardizes communication system functions into seven different levels. In processing data as it goes from one device to another, each layer has a specific function. The layers are Application, Presentation, Session, Transport, Network, Data Link, and Physical, listed in order of decreasing importance. Understanding and troubleshooting network protocols and services are made easier by these layers.

4. What is a subnet mask?

Ans:

A subnet mask is a 32-bit binary value that is used in networking to separate an IP address into its network and host components. Usually, it is shown using dotted decimal notation. It specifies the portions of an IP address that identify the network and the host, respectively. In order to route traffic within a network and identify the devices connected to the same local network segment, subnet masks are crucial.

5. Differentiate between a hub and a switch.

Ans:

Hub: An elementary networking tool that works at the physical layer is a hub. (Layer 1) and simply broadcast incoming data to all devices connected to it. This means that all devices on a hub receive all data frames, regardless of whether they are the intended recipient, leading to network congestion and reduced efficiency.
Switch:In contrast, a switch operates at the data link layer (Layer 2) and is more intelligent. It uses MAC addresses to forward data frames only to the specific device for which the data is intended. This improves network performance by reducing unnecessary traffic and collisions.

 

6. What is a router?

Ans:

A network device that works at the network layer is a router (Layer 3) of the OSI model. Its primary function is to connect different networks and make intelligent decisions about where to forward data packets based on destination IP addresses. Routers play a critical role in directing traffic between LANs, WANs, and the internet.

7. Explain NAT (Network Address Translation).

Ans:

  NAT is a network protocol and technology used to conserve public IP addresses and enhance network security. It allows multiple devices on a private network to share a single public IP address when accessing resources on the internet. NAT translates private IP addresses into a single public IP address when data leaves the private network and restores the original private addresses when responses return.

8. What is a VLAN (Virtual LAN)?

Ans:

 A VLAN is a logical segmentation of a physical network into smaller, isolated broadcast domains. It is used to enhance network security, simplify network management, and improve network performance. VLANs are typically configured on managed switches and can group devices by department, function, or security requirements, regardless of their physical location on the network. 

9. Define DHCP (Dynamic Host Configuration Protocol).

Ans:

A computerized network technology called DHCP automates the assignment of IP addresses, subnet masks, default gateways, DNS server addresses, as well as other network device configuration data. DHCP servers dynamically allocate and manage IP addresses, simplifying network administration and ensuring efficient IP resource utilization.

10. What is a DNS server?

Ans:

A crucial element of the internet is the DNS (Domain Name System) server, which converts human-readable domain names (such as www.example.com) into IP addresses (such as 192.168.1.1) that computers use to locate resources on the network. DNS plays a fundamental role in Internet communication by facilitating user-friendly web browsing and resource discovery. It operates using a hierarchical distributed database system that allows efficient domain name resolution.

11.  What is a firewall?

Ans:

A firewall is a piece of hardware or software used in network security that serves as a wall between a trusted network, such an internal corporate network, and an untrusted network, like the Internet. It enforces security policies by inspecting and controlling incoming and outgoing network traffic, ensuring that only authorized traffic is allowed and potentially harmful traffic is blocked. Firewalls can operate at various layers of the OSI model and use rules and policies to filter traffic based on factors like source/destination IP addresses, port numbers, and protocols.

 12. Explain the difference between TCP and UDP.

Ans:

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are both transport layer protocols, but they have key differences. TCP provides reliable, connection-oriented communication, meaning it guarantees the delivery of data packets, handles retransmissions in case of packet loss, and ensures data arrives in the correct order. UDP, on the other hand, is connectionless and offers faster, but less reliable communication. It doesn’t guarantee the delivery or sequencing of packets and is often used for real-time applications like video streaming and VoIP.

13. What is a default gateway?

Ans:

A default gateway is a network device (usually a router) that serves as the exit point for traffic from devices on a local network to reach destinations outside of that network, such as other subnets or the internet. Devices on the local network use the default gateway’s IP address as the next hop for any traffic bound for external networks. The default gateway is crucial for routing data between different network segments.

14. What is a static route?

Ans:

A static route is a routing entry that has been manually configured in a router’s routing table. It defines a specific path for network traffic to follow when reaching a particular destination network or subnet. Unlike dynamic routing protocols, which adapt to changes in network topology automatically, static routes are configured by network administrators and remain fixed until manually updated. They are commonly used for specific routing requirements or to override default routing behavior.

15.  Describe the purpose of ARP (Address Resolution Protocol).

Ans:

In Ethernet networks, ARP is used to translate an IP address to its matching MAC address. When a device on a local network needs to send data to another device, it uses ARP to discover the MAC address associated with the destination IP address. This information is essential for the device to create Ethernet frames and successfully transmit data within the local network.

16. What is a subnet?

Ans:

A subnet, short for subnetwork, is a logical division of a larger IP network into smaller, more manageable segments. Subnetting allows network administrators to create separate broadcast domains, control traffic flow, and apply security policies at a finer-grained level. It also optimizes IP address allocation, reducing IP address waste.

17. Explain the purpose of ICMP (Internet Control Message Protocol).

Ans:

ICMP is a network protocol used for error reporting and diagnostic functions in IP networks. It provides feedback about network conditions and helps troubleshoot network issues. ICMP includes utilities like the ping command, which tests network connectivity by sending ICMP echo request packets to a destination host and waiting for an echo reply.

18. What is a broadcast domain?

Ans:

A broadcast domain is a group of devices within a network that can receive broadcast messages from each other. Broadcasts are typically used for various network management and discovery functions. In a switched network, each VLAN represents a separate broadcast domain, ensuring that broadcast traffic is isolated to devices within the same VLAN.

19. What is a collision domain?

Ans:

A collision domain is a network segment where data collisions can occur on shared communication channels, primarily in Ethernet networks that use hubs. When multiple devices transmit data simultaneously on a shared medium, collisions can lead to degraded network performance and increased latency. Switched networks reduce collision domains as they isolate traffic on separate ports.

20. Define QoS (Quality of Service).

Ans:

Quality of Service (QoS) is a set of networking technologies and mechanisms used to prioritize and manage network traffic to ensure the delivery of higher-quality services to specific applications, users, or traffic classes. When network resources are allocated properly, congestion is reduced, and key applications are given the bandwidth and low latency they require to operate efficiently. It is essential for maintaining good network performance and user experience in environments with diverse traffic requirements.

 21. What is a loopback address?

Ans:

A loopback address, commonly represented as 127.0.0.1 in IPv4, is a special IP address used to establish communication within the same device. It allows a device to test its network stack without actually sending data over a physical network. Loopback addresses are often used for local testing and troubleshooting network configurations.

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    22. What is SSH (Secure Shell)?

    Ans:

    SSH is a cryptographic network protocol used for secure remote access as well as data management and transfer between networked devices. Sensitive information is shielded from listening devices and illegal access thanks to the encryption of the communication between the client and server. SSH is frequently used to establish secure connections with servers, switches, and routers.

    23.   Explain the purpose of ACLs (Access Control Lists).

    Ans:

    Access Control Lists (ACLs) are used to control and filter network traffic based on predefined rules. Depending on different factors such source and destination IP addresses, port numbers, and protocols, these rules can allow or refuse traffic. ACLs are commonly implemented on routers and firewalls to enforce security policies and control traffic flow.

    24. What is a subnetting mask?

    Ans:

    In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.  

    25. What is a gateway of last resort?

    Ans:

    A gateway of last resort, also known as a default gateway or default route, is a routing entry that specifies where network traffic should be forwarded if there is no specific route defined for the destination. It acts as a catch-all route, ensuring that any traffic not covered by more specific routes is sent to a designated gateway for further routing.

     

    26. What is STP (Spanning Tree Protocol)?

    Ans:

    Spanning Tree Protocol is a network protocol that prevents loops in Ethernet networks by dynamically disabling redundant links. It ensures a loop-free logical topology, which is crucial for network stability and preventing broadcast storms. STP elects a root bridge and calculates the best path for forwarding traffic while blocking or disabling redundant paths.

     27.  What is a DNS resolver?

    Ans:

    A DNS resolver is a software component or service that queries DNS servers to resolve domain names into IP addresses. It is essential to the domain name resolution procedure because it guarantees that users may access websites and services with domain names that are human-readable.   

    28.  What is NAT overload (PAT)?

    Ans:

     A variant of Network Address Translation (NAT) is NAT overload, often referred to as Port Address Translation (PAT). It enables the sharing of a single public IP address between a number of private IP addresses by using various source port numbers to distinguish between connections. To preserve public IP addresses, PAT is frequently used in home routers and small office networks.

    29. What is a subnet mask?

    Ans:

    A subnet mask is a 32-bit value used in IP networking to separate the network and host portions of an IP address. It consists of consecutive ‘1’s in binary notation for the network portion and ‘0’s for the host portion. Subnet masks are crucial for routing decisions and determining the range of IP addresses within a subnet.

    30.  What is the purpose of VLSM (Variable Length Subnet Masking)?

    Ans:

    Variable Length Subnet Masking (VLSM) is a technique that allows subnet masks of varying lengths to be applied within the same IP network. This enables more efficient allocation of IP addresses by subnetting subnets further, thus reducing IP address wastage. VLSM is commonly used in hierarchical network designs to optimize IP address utilization.

    31. What is BGP (Border Gateway Protocol)?

    Ans:

      In order to exchange routing and reachability data between autonomous systems (ASes) on the internet, the Border Gateway Protocol (BGP) is an outer gateway protocol. BGP plays a critical role in determining the best path for data to traverse the global internet, making it a core routing protocol for internet service providers and large networks.

    32. Explain the concept of a DMZ (Demilitarized Zone).

    Ans:

    An organization’s internal network and an external network, usually the internet, are separated by a network segment called a “DMZ.” It is used to host servers and services that need to be accessible from the internet while maintaining a layer of security by isolating them from the internal network. DMZs are commonly used to host web servers, email servers, and public-facing services.

    33. What is the purpose of SNMP (Simple Network Management Protocol)?

    Ans:

    A network section known as a “DMZ” divides an organization’s internal network from an external network, typically the internet. It is used to host servers and services that need to be accessible from the internet while maintaining a layer of security by isolating them from the internal network. DMZs are commonly used to host web servers, email servers, and public-facing services.

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     34. What is the difference between RIP and IGRP?

    Ans:

    Following are the differences between RIP and IGRP:

    Basis of Comparison     RIP IGRP
    Full form RIP stands for routing information protocol. IGRP stands for interior gateway routing protocol
    Description RIP is a distance vector-based routing protocol IGRP is a distance vector based interior gateway
    routing protocol
    Determination of route RIP depends on the number of hops to determine the
    best route to the network.
    IGRP considers many factors before deciding the best
    route to take, i.e., bandwidth, reliability, MTU and hops count.
    Standard RIP is an industry standard dynamic protocol. IGRP is a Cisco standard dynamic protocol
    Organization used RIP is mainly used for smaller sized organizations IGRP is mainly used for medium to large-sized
    organizations
    Maximum routers It supports a maximum of 15 routers It supports a maximum of 255 routers
    Symbol used RIP is denoted by ‘R’ in the routing table IGRP is denoted by ‘I’ in the routing table
    Administrative distance The administrative distance of RIP is 120 The administrative distance of IGRP is 100
    Algorithm RIP works on Bellman ford Algorithm IGRP works on Bellman Ford Algorithm

    35. What is a proxy server?

    Ans:

    A network section known as a “DMZ” divides an organization’s internal network from an external network, typically the internet. It acts as a gateway for client requests, forwarding them to the appropriate destination. Proxy servers are used for various purposes, including security, content filtering, and load balancing. They can enhance privacy and security by hiding the client’s IP address and caching frequently requested content.

    36. What is the purpose of HSRP (Hot Standby Router Protocol)?

    Ans:

    A Cisco-exclusive redundancy mechanism called the Hot Standby Router mechanism (HSRP) is used to ensure high availability for routers and default gateways. HSRP allows multiple routers to work together in an active-standby configuration, ensuring uninterrupted network access in case the active router fails. It is often used in scenarios where network uptime is critical.

    37.  What is OSPF (Open Shortest Path First)?

    Ans:

    An inside gateway routing protocol used in autonomous systems or networks is called Open Shortest Path First (OSPF). It is designed to determine the best path for routing traffic based on various metrics, such as link cost. OSPF is a link-state routing protocol, meaning routers exchange information about their network topology to calculate optimal routes dynamically.

    38. What is an 802.1Q VLAN trunk?

    Ans:

    802.1Q is an IEEE standard for Virtual LAN (VLAN) tagging in Ethernet frames. A VLAN trunk is a network link that carries traffic from multiple VLANs over a single physical connection. It uses 802.1Q tagging to identify which VLAN each frame belongs to, allowing multiple VLANs to coexist on the same trunked link. VLAN trunks are commonly used to connect switches and route traffic between VLANs.

    39. What is RADIUS (Remote Authentication Dial-In User Service)?

    Ans:

    RADIUS is a network protocol and authentication, authorization, and accounting (AAA) protocol used for managing access to network resources. It provides centralized authentication and authorization services, making it a common choice for securing access to network devices, wireless networks, and VPNs.

    40. What is ARP poisoning (ARP spoofing)?

    Ans:

    ARP poisoning, often referred to as ARP spoofing, is a network attack in which a hacker sends forged Address Resolution Protocol (ARP) packets to link their MAC address to the IP address of a trusted device on the network. This allows the attacker to intercept or manipulate network traffic, potentially leading to security breaches or eavesdropping. ARP poisoning attacks can be mitigated using techniques like static ARP entries or ARP inspection.

    41. What is the purpose of NAT64?

    Ans:

    NAT64 is a network technology that facilitates communication between IPv6-only and IPv4-only devices. It translates IPv6 packets into IPv4 packets and vice versa, enabling devices using different IP versions to communicate across the internet. NAT64 is essential during the transition from IPv4 to IPv6.

    42. What is BGP (Border Gateway Protocol) AS-path prepending?

    Ans:

     BGP AS-path prepending is a technique used to influence the BGP route selection process by adding one’s own autonomous system (AS) number multiple times to the AS-path attribute of BGP route announcements. This makes the route appear less attractive to neighboring ASes, diverting traffic away from the AS performing the prepending.

     43. Explain the purpose of VLAN pruning.

    Ans:

    VLAN pruning is a feature used in switched networks to optimize bandwidth utilization by restricting the propagation of unnecessary broadcast and multicast traffic. It dynamically prunes VLANs from trunk links if they do not have active ports in the neighboring switches, reducing unnecessary broadcast domains.

    44. What is the purpose of a Honeypot in network security?

    Ans:

    A Honeypot is a decoy system or network designed to attract and monitor malicious activity. It is used in network security to detect and analyze threats, gain insights into attacker behavior, and gather information about emerging threats. Honeypots are intentionally vulnerable systems that lure attackers away from critical network resources. 

    45.  What is NAT-PMP (NAT Port Mapping Protocol)?

    Ans:

    NAT-PMP is a protocol used for network address translation (NAT) traversal in home routers and residential networks. It allows devices within a private network to automatically request and manage port mappings on the NAT device, enabling applications like online gaming and peer-to-peer file sharing to function correctly.

    46.  What is the purpose of Q-in-Q (802.1ad) in Ethernet networks?

    Ans:

    Q-in-Q, also known as IEEE 802.1ad or Provider Bridges, is an Ethernet standard that allows multiple VLAN tags to be added to an Ethernet frame. It is commonly used in service provider networks to provide VLAN stacking or tunneling, allowing customer VLANs to be transported over a service provider’s network while maintaining isolation and segregation.

    47. What is EIGRP (Enhanced Interior Gateway Routing Protocol)?

    Ans:

    Proxy ARP is a feature where a network device, typically a router, responds to ARP requests on behalf of another device within the same subnet. It is used when devices need to communicate even though they are not directly reachable in the local network segment. Proxy ARP helps devices find a route to reach other devices without using static routing.

    48. What is the purpose of a proxy ARP?

    Ans:

    The Time to Live (TTL) field prevents “lost” packets from being passed endlessly through the IP internetwork. The field contains an 8-bit integer that is set by the originator of the packet. Each router through which the packet passes will decrement the integer by one. If a router decrements the TTL to zero, it will discard the packet and send an ICMP “time exceeded” error message to the packet’s source address.

    49. What is the purpose of NVRAM (Non-Volatile RAM) in Cisco routers and switches?

    Ans:

    NVRAM is a type of memory used in Cisco routers and switches to store the startup configuration, which is the configuration that is loaded when the device is powered on or rebooted. It retains the configuration even after a power loss, ensuring that network devices maintain their configuration settings across reboots.

    50. What is the purpose of DHCP snooping in network security?

    Ans:

    DHCP snooping is a security feature used to prevent unauthorized or malicious DHCP servers on a network. It monitors DHCP traffic and verifies the legitimacy of DHCP server responses. By filtering out unauthorized DHCP offers, it prevents devices from obtaining IP addresses from rogue DHCP servers, reducing the risk of network attacks.

    51. What is the purpose of ARP poisoning (ARP spoofing) detection mechanisms in network security?

    ARP poisoning detection mechanisms are used to identify and mitigate ARP spoofing attacks. These mechanisms monitor ARP traffic and detect inconsistencies, such as multiple MAC addresses associated with a single IP address. When ARP poisoning is detected, the network can take corrective actions like alerting administrators or blocking the offending device.

    52. Explain the purpose of NAT64 and NAT46 in IPv6 migration.

    Ans:

    NAT64 and NAT46 are translation mechanisms used during the transition from IPv4 to IPv6. NAT64 allows IPv6-only devices to access IPv4 resources by translating IPv6 packets into IPv4 packets. Conversely, NAT46 enables IPv4-only devices to communicate with IPv6 resources by performing the reverse translation. These mechanisms facilitate interoperability between IPv4 and IPv6 networks. 

    53. What is a BGP (Border Gateway Protocol) route reflector and why is it used?

    Ans:

    BGP route reflector is a BGP feature used in large-scale networks to simplify the BGP topology. In a typical BGP configuration, routers form a full mesh, which can be impractical in networks with numerous BGP peers. Route reflectors reduce the complexity by allowing some routers to reflect BGP routes to others, reducing the number of required BGP peerings.

    54. What is the purpose of VTP (VLAN Trunking Protocol) in Cisco networks?

    Ans:

    VTP is a Cisco protocol used to manage VLAN configurations across multiple switches in a network. It ensures consistency in VLAN naming and numbering, making it easier to manage VLANs on a large scale. VTP propagates VLAN information to switches within the same VTP domain, simplifying VLAN configuration and reducing the risk of misconfigurations.

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    55. What is LACP (Link Aggregation Control Protocol)?

    Ans:

    LACP, also known as IEEE 802.3ad or EtherChannel, is a protocol used to combine multiple physical Ethernet links into a single logical link, increasing bandwidth and providing redundancy. It is commonly used to aggregate links between switches and routers or between switches, enhancing network performance and fault tolerance.

    56. What is an AnyConnect VPN in Cisco networking?

    Ans:

    Cisco AnyConnect is a VPN client and secure mobility application used to establish encrypted connections to corporate networks. It provides remote users with secure access to company resources over the internet. AnyConnect supports various VPN protocols, including SSL, IPsec, and IKEv2, making it versatile for different network configurations and security requirements.

    57.  What is the purpose of ARP poisoning (ARP spoofing) prevention mechanisms in network security?

    Ans:

    ARP poisoning prevention mechanisms are designed to protect networks from ARP spoofing attacks. These mechanisms include features like ARP inspection and dynamic ARP inspection, which monitor and validate ARP traffic to ensure that ARP packets match the legitimate mapping of IP addresses to MAC addresses, thereby preventing spoofing.

    58. What is the purpose of a VRRP (Virtual Router Redundancy Protocol)?

    Ans:

    A network protocol called Virtual Router Redundancy Protocol (VRRP) is used to give routers on a LAN high availability. An active-standby arrangement, it enables many routers to cooperate, guaranteeing that one router takes over in the event that the primary router malfunctions. When a router fails, VRRP preserves network continuity and reduces downtime.

    59.  What is the purpose of GRE (Generic Routing Encapsulation) in networking?

    Ans:

    A number of network layer protocols are encapsulated into point-to-point connections using the tunnelling protocol GRE. It is commonly used to create virtual private networks (VPNs) or establish direct communication between remote networks over an insecure or public network, such as the internet. GRE provides a flexible and extensible way to transport traffic securely between endpoints.

    60. What is HSRP (Hot Standby Router Protocol) Virtual IP address?

    Ans:

    In HSRP, the Virtual IP (VIP) address is a shared IP address used as the default gateway for devices in the local network. It floats between the active and standby routers in an HSRP group. If the active router fails, the VIP is moved to the standby router to ensure uninterrupted network access.

    61. What is the purpose of 802.1X authentication in network security?

    Ans:

    IEEE standard 802.1X defines port-based network access control. It provides a framework for authenticating and authorizing devices before granting access to a network. 802.1X is commonly used for wired and wireless network security to ensure that only authorized devices can connect.

    62.  What is PIM (Protocol Independent Multicast)?

    Ans:

    In IP networks, multicast traffic is routed using the Protocol Independent Multicast (PIM) protocol. PIM enables routers to dynamically learn and maintain multicast group memberships and efficiently forward multicast traffic to only those network segments with active receivers. PIM operates independently of the unicast routing protocol.

    63.  How do areas benefit a link state inter network?

    Ans:

    Within a routing domain, areas are subdomains. They make link state routing more efficient by limiting the size of the link state database of each router in the area.

    64. What is VTP pruning in Cisco networks?

    Ans:

    VTP pruning is a feature in Cisco networks that helps optimize bandwidth usage in VLAN configurations. It prevents broadcast traffic from being sent to VLANs that don’t have active ports in neighboring switches. This reduces unnecessary broadcast traffic and enhances network performance.

    65. What is the purpose of LLDP (Link Layer Discovery Protocol) in networking?

    Ans:

    Link Layer Discovery Protocol (LLDP) is a vendor-neutral network protocol used to discover and advertise device information on a local network segment. LLDP enables devices to share details such as device type, capabilities, and management addresses. It is often used for network monitoring and device management.

    66. What is a VRF (Virtual Routing and Forwarding) in networking?

    Ans:

    Link Layer Discovery Protocol (LLDP) is a vendor-neutral network protocol used to discover and advertise device information on a local network segment. LLDP enables devices to share details such as device type, capabilities, and management addresses. It is often used for network monitoring and device management.

    67. Explain the purpose of PaaS (Platform as a Service) in cloud computing.

    Ans:

    Platform as a Service (PaaS) is a cloud computing service model that provides a platform and environment for developers to build, deploy, and manage applications without worrying about the underlying infrastructure. PaaS offerings include development tools, databases, and runtime environments, simplifying the application development and deployment process.

    68. What is the difference between a stateful and stateless firewall?

    Ans:

    Stateful firewalls make judgments based on the state table and maintain track of the status of active connections. Depending on how closely they relate to established connections, it can examine the condition of packets and either allow or prohibit them. On the other hand, a stateless firewall does not take the connection’s state into account while filtering packets; instead, it only looks at the characteristics of each individual packet

    69. What is EVPN (Ethernet VPN) in networking?

    Ans:

    Ethernet VPN (EVPN) is a network technology that extends Layer 2 Ethernet services across data center and wide-area networks. It is commonly used in data center interconnects, enabling efficient and flexible communication between data centers and facilitating network virtualization and automation. EVPN uses BGP as its control plane protocol.

    70. What is the purpose of NTP (Network Time Protocol)?

    Ans:

    8 Devices on a network can have their clocks synchronized using the Network Time Protocol (NTP). It ensures that devices have accurate and synchronized time, which is crucial for various network operations, security protocols, and event logging. NTP servers provide time information to client devices, helping maintain consistency across the network.

    71.  What is the purpose of ICMPv6 (Internet Control Message Protocol version 6)?

    ICMPv6 is the IPv6 counterpart of ICMP used in IPv4. It serves various purposes, including error reporting, diagnostics, and network management. ICMPv6 includes functionalities like Neighbor Discovery Protocol (NDP) for address resolution, router discovery, and autoconfiguration, making it essential for IPv6 networks.

    72. What is MTU?

    Ans:

    ICMPv6 is the IPv6 counterpart of ICMP used in IPv4. It serves various purposes, including error reporting, diagnostics, and network management. ICMPv6 includes functionalities like Neighbor Discovery Protocol (NDP) for address resolution, router discovery, and autoconfiguration, making it essential for IPv6 networks.

    73. What is SDN (Software-Defined Networking)?

    Ans:

    The architectural method known as “Software-Defined Networking” (SDN) divides the control plane from the data plane of network devices. It centralizes network control and management through software controllers, making networks more flexible, programmable, and adaptable to changing requirements. SDN allows for efficient traffic engineering, network automation, and dynamic resource allocation.

    74. What is the purpose of BFD (Bidirectional Forwarding Detection) in networking?

    Ans:

    A network technique called Bidirectional Forwarding Detection (BFD) is used in IP networks to quickly identify link or path problems. BFD provides faster convergence times than traditional routing protocols, making it suitable for detecting failures in milliseconds and improving network reliability.

    75. What is the purpose of 802.1QinQ (Provider Bridging or Double Tagging) in Ethernet networks?

    Ans:

    802.1QinQ is an extension of the VLAN tagging standard (802.1Q) that allows for multiple layers of VLAN tagging within an Ethernet frame. It is commonly used by service providers to transport customer VLANs over a provider’s network while maintaining isolation between customer traffic. Each customer’s VLAN traffic is encapsulated with two VLAN tags: one for the customer’s VLAN and one for the provider’s VLAN.

    76. What is the purpose of BGP communities in Border Gateway Protocol (BGP)?

    BGP communities are a mechanism for tagging and grouping BGP routes with similar characteristics. Network operators use BGP communities to define policies and attributes for route manipulation, such as preferring one path over another or controlling route redistribution. Communities help simplify BGP route management and control.

    77. What is VTP (VLAN Trunking Protocol) pruning in Cisco networks?

    Ans:

    VTP pruning is a feature in Cisco networks that helps optimize the distribution of broadcast and multicast traffic in VLAN configurations. It prevents broadcast traffic from being sent to VLANs that don’t have active ports in neighboring switches. This reduces unnecessary broadcast traffic and enhances network performance.

    78. What is the purpose of a Bastion Host in network security?

    Ans:

    A Bastion Host, also known as a jump server or a pivot server, is a highly secure and monitored server placed at the perimeter of a network. It acts as a single entry point for remote administrators to access the internal network. Bastion hosts are used to minimize the attack surface, control access, and monitor administrative activities.

    79. What is EIGRP (Enhanced Interior Gateway Routing Protocol) Wide Metric mode?

    Ans:

    EIGRP Wide Metric mode is an extension of EIGRP designed to support large-scale networks with more than 32,000 routes. It uses 64-bit metric values, allowing EIGRP to accommodate larger routing tables and scale to networks with extensive route information.

    80. What is the purpose of RSTP (Rapid Spanning Tree Protocol) in Ethernet networks?

    Ans:

    Rapid Spanning Tree Protocol (RSTP) is an evolution of the Spanning Tree Protocol (STP) designed to provide faster convergence in Ethernet networks. RSTP reduces the time it takes to transition ports from blocking to forwarding states, resulting in quicker network recovery in the event of topology changes or link failures. It is backward-compatible with STP.

    81.  Explain what is EIGRP?

    Ans:

    EIGRP stands for Enhanced Interior Gateway Routing Protocol; it is a routing protocol designed by Cisco Systems. It is availed on a router to share routes with other routers within the same autonomous system. Unlike other routers like RIP, EIGRP only sends incremental updates, decreasing the workload on the router and the amount of data which needs to be transferred.

    82. Which are the two types of available cables?

    Ans:

    A development of the Spanning Tree Protocol (STP), Rapid Spanning Tree Protocol (RSTP) aims to accelerate convergence on Ethernet networks. RSTP reduces the time it takes to transition ports from blocking to forwarding states, resulting in quicker network recovery in the event of topology changes or link failures. It is backward-compatible with STP.

    83. What is the purpose of VLAN access control lists (VACLs) in network security?

    Ans:

    VACLs, or VLAN access control lists, are used to filter traffic inside a particular VLAN. They let network administrators create policies that allow or disallow traffic depending on a range of factors, including source and destination MAC addresses, IP addresses, or protocols. Within VLANs, VACLs add another level of protection.

    84. What is the difference between TACACS+ and RADIUS in network authentication and authorization?

    Ans:

    TACACS+ and RADIUS are both protocols used for authentication, authorization, and accounting (AAA) in network access control. The main difference is that TACACS+ offers separate authentication and authorization processes, while RADIUS combines authentication and authorization into a single process. TACACS+ is often preferred for more granular control and detailed logging.

    85. What is the purpose of DHCPv6 (Dynamic Host Configuration Protocol for IPv6)?

    Ans:

    DHCPv6 is used to automatically configure IPv6 addresses and other network parameters for devices on an IPv6 network. It provides a central point for managing IP address allocation and allows devices to obtain IPv6 addresses, DNS server information, and other configuration details without manual intervention.

    86. What is the purpose of HSRP (Hot Standby Router Protocol) object tracking in network redundancy?

    Ans:

    HSRP object tracking is a feature that allows routers to adjust their HSRP priority based on the status of specific tracked objects, such as interfaces or routes. If a tracked object becomes unavailable, the router’s priority is lowered, causing it to relinquish the role of the active router. This feature enhances network redundancy by dynamically adapting to changing conditions.

    87. What is a Network ACL (Access Control List) in network security?

    Ans:

    A Network ACL is a set of rules that control the flow of traffic entering or leaving a network or subnet. It can be implemented on routers or firewalls to permit or deny traffic based on criteria such as source/destination IP addresses, port numbers, and protocols. Network ACLs help enforce security policies and protect network resources from unauthorized access.

    88. What is OSPF (Open Shortest Path First) Type 3 LSA (Link-State Advertisement)?

    Ans:

    OSPF Type 3 LSAs, also known as Summary LSAs or Inter-Area Prefix LSAs, are used in OSPF to advertise routes from one OSPF area to another. They summarize information about networks within an area, allowing routers in one area to learn about routes in other areas. Type 3 LSAs play a crucial role in OSPF hierarchical network design.

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    89. What is the purpose of SNMP traps in network management?

    Ans:

    SNMP traps are unsolicited messages sent by network devices to a central SNMP manager or monitoring system. They are used to notify the manager of significant events or conditions on the network, such as link failures, interface errors, or device reboots. SNMP traps provide real-time alerts and are essential for proactive network monitoring and troubleshooting.

    90. What is the difference between NAT (Network Address Translation) and PAT (Port Address Translation)?

    Ans:

    NAT and PAT are both techniques used to map private IP addresses to a public IP address for communication over the internet. The key difference is that NAT maps one private IP address to one public IP address, while PAT maps multiple private IP addresses to a single public IP address by using unique source port numbers to distinguish between connections. PAT is more commonly used due to IP address scarcity.

    91. What is the purpose of GRE (Generic Routing Encapsulation) keepalives in tunneling protocols?

    Ans:

    GRE keepalives are used to ensure the health and availability of GRE tunnels. They allow devices at both ends of the tunnel to periodically exchange keepalive packets. If a device stops receiving keepalives from the other end, it can detect tunnel failures and take appropriate action, such as tearing down the tunnel or initiating a failover.

    92. What is the purpose of a NAC (Network Access Control) system in network security?

    Ans:

    Using the identification and compliance status of users and devices, Network Access Control (NAC) is a security solution that enforces security regulations and controls access to a network. NAC systems perform tasks such as device authentication, posture assessment, and remediation, ensuring that only authorized and healthy devices gain access to the network. NAC enhances network security and compliance.

    93. What is the purpose of a BGP confederation in Border Gateway Protocol (BGP)?

    Ans:

    A BGP confederation is a mechanism used to divide a large Autonomous System (AS) into smaller sub-ASes, each with its own internal BGP (iBGP) and external BGP (eBGP) relationships. Confederations help manage the complexity of large networks and allow for more manageable BGP configurations.

    94. What is the difference between half-duplex and full-duplex communication in Ethernet networks?

    Ans:

    In half-duplex communication, devices can either transmit or receive data but not both simultaneously. In full-duplex communication, devices can transmit and receive data simultaneously, allowing for faster and more efficient communication. Ethernet switches and modern network interfaces typically operate in full-duplex mode, improving network performance.

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