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CCNA is a stepping stone for getting quality jobs and career growth. It helps to get into the networking domain, especially if one wants to work with CISCO products. Before you start your career as a professional CCNA expert, you will DEFINITELY get help from these CCNA interview questions and answers. It enhances your knowledge to a great level and helps you crack a CCNA interview successfully at a fresher and experienced level. 

OSPF (Open Shortest Path First) is basically a popular link-state routing protocol for IP networks that are used to connect to a large number of networks without any limitation on the number of hops. It DETERMINES the best route for delivering the data packets WITHIN an IP network.  It has been implemented by a wide range of network vendors such as Cisco. It works on Dijkstra Algorithm. 

• Firstly, a shortest-path TREE is constructed. 
• Secondly, the routing table is POPULATED with the resulting best paths. 

PoE (Power on Ethernet) GENERALLY refers to a TECHNOLOGY that allows ELECTRIC power to be carried over the Ethernet cable that carries data. It passes the electric power SUPPLY to the network through the cable rather than the power cords and MINIMIZES the number of wires required to install the network.

The application layer is the topmost layer in the OSI model that is USED by end-user software such as web browsers and email clients. It is considered as the layer through which users interact. It usually consists of some protocols that are more focused on process-to-process communication across an IP Network. Some of its FUNCTIONS include: 

• Manage data exchange in a peer-to-peer or a client-server networking model.  
• Provide FIRM communication interface and end-user services. 
• Enables users to access the network. 
• Provide the basis for email forwarding and storage FACILITIES. 
• Allows access to global INFORMATION about different services. 

Different types of passwords that can be used in CISCO routers include: 

• Enabled: This is a GLOBAL command that disables privileged execution mode. The password is not ENCRYPTED. To change it, one can USE  "enable password password"
• Enable Secret: In place of an enable password, this secret password is used.  To change it, one can use "enable secret password".
• AUX (Auxiliary): Passwords for auxiliary ports can be set using an auxiliary password. Through a modem, a router can be accessed via this port.
• Console: Console port passwords are set using the console password.
• VTY (Virtual Terminal): For Telnet SESSIONS into the router, you will need the virtual terminal password. Passwords can be changed at any time. You can set it up when you configure the router from the console. 

Two types of networks in CCNA includes: 

Server-based network: Client-Server networks can ALSO be REFERRED to as Server-Based networks. A server is a node that provides SERVICES to CLIENTS. In this, a Centralized server is used to store the data because its management is centralized.

Peer-to-Peer network: A peer-to-peer network is also known as a computer-to-computer network or P2P. Peers are nodes or computer systems that are connected to one another. Every node in this kind of network is connected to another node.

Network congestion is a situation that occurs when a network node is overloaded with data or traffic and can cause a common problem for admins. It USUALLY occurs when the network is carrying or EXCHANGING more data than the network devices like routers and switches can accommodate. It is a result of an internet route becoming too full when MANY users try USING the same BANDWIDTH. This condition is true in big networks that do not resort to network segmentation.

Static IP address: Static IP address, as the NAME suggests, is simply an IP address that doesn’t change. It remains the same until the device is decommissioned or the network architecture is changed.  

Dynamic IP address: Dynamic IP address, as the name suggests, is simply an IP address that changes over time. It is mostly used because IPv4 does not provide enough static IP addresses to go around. 

Static vs Dynamic IP address:

Route poisoning refers to a method that prevents certain networks from sending data PACKETS to PATH destinations that have already become invalid. This method is being employed by distance vector routing protocols like RIPv2 whenever they see any invalid route to prevent routing loops. It is generally used to overcome large routing loops and informs all the connected routers in a NETWORK about the path that is invalid by saying that it has a hop count that exceeds the MAXIMUM allowable. 

BOOTP (Bootstrap Protocol or Boot Program) is defined as a computer networking protocol that is being used by a client for obtaining an IP address of a server PC. In a network, BootP is generally used for booting diskless WORKSTATIONS. These diskless workstations use BootP to get their own IP address as WELL as the server’s IP address.  It was ORIGINALLY designed to replace RARP (Reverse Address RESOLUTION Protocol), also known as RFC 903. 

Broadcast Domain: As the NAME suggests, a Broadcast domain is a logical set of reachable computer systems without having a router. In this TYPE of domain, traffic flows all over the network. In this scenario, when a device sends a broadcast message, then all the other devices present in its broadcast domain have to pay attention to it.  

Collision Domain: As the name suggests, a Collision domain is a part of a network where PACKET collisions can take place when being sent on a shared medium or through REPEATERS. In this scenario, when a device sends a message to a network, then all other devices present in its collision domain have to pay attention to it, whether or not it was destined for them. 

There are SEVERAL ADVANTAGES of using VLAN:  

• Removes latency and traffic load on the network 
• Saves network resources and increases network efficiency 
• Reduces IT cost and the incidence of collisions 
• Improve network security and PERFORMANCE 
• Ensure network flexibility and provide easier management 
• Make it easier to RELOCATE a network or a network device 
• Increase the number of broadcast DOMAINS while decreasing the size of broadcast domains. 
• Establish broadcast domains in switched networks. 

VLAN (Virtual Local Area Network) is basically a logical group of workstations, services, or network DEVICES that communicate with one another on a separate physical LAN. It improves the network performance or applies some additional security features. It ALSO allows SEVERAL networks to work virtually as if they were a LAN SHARING a single broadcast DOMAIN. 

CDP (Cisco Discovery Protocol) is a Layer 2, media-independent, and network-independent protocol that runs on all the Cisco devices that helps US to discover Cisco devices on the network. This protocol works on the basis of MAC address. It also facilitates the management of Cisco devices by discovering these devices, identifying how to configure them, and allowing systems to learn about each other using different network-layer protocols. Some of its functions include: 

• Collects INFORMATION about directly connected neighboring devices.  
• Find adjacent Cisco devices. 
• Find out port numbers, IP addresses, router models, switch models, interface details, IOS details, device ID-hostname. 
• Simplifies the process of keeping an up-to-date inventory of Cisco network devices. 
• Share information about other directly connected Cisco equipment like OS version, IP addresses. 

EIGRP (Enhanced Interior Gateway Routing Protocol) is referred to as Cisco's IGP (Interior Gateway Protocol) that is USED on a computer network ESPECIALLY for automating routing decisions and configurations. This protocol is suited for DIFFERENT topologies and media. It is mostly used on a router to share routes with other ROUTERS within the same autonomous SYSTEM.  

EIGRP Protocol generally includes the following metrics: 

• Bandwidth 
• Load 
• Delay 
• Reliability 
• MTU 
• Maximum Transmission Unit