Cables between Networking Devices

• Router and Switch --> Straight Cable
• Switch and Switch --> Crossover Cable
• Router and Router --> Crossover Cable
• Switch and PC ---> Straight Cable

Thumbs Rule :

Similar devices --> Crossover Cable

Different devices ---> Straight Cable

CCNA Interview Questions and Answers

 CCNA Interview Questions and Answers 

Question 1 – Tell us something about OSI Model ?

❑ OSI stands for Open Systems Interconnection.

❑ It has been developed by ISO – ‘International Organization of Standardization‘, in the year 1984.

❑ It is a reference model and have  7 layer architecture with each layer having specific functionality to perform.

 

Question 2 – What are the 7 layers in OSI Model ? 

❑ Layer 1 - Physical Layer       

❑ Layer 2 - Data Link Layer 

❑ Layer 3 - Network Layer

❑ Layer 4 - Transport Layer 

❑ Layer 5 - Session Layer

❑ Layer 6 - Presentation Layer

❑ Layer 7 - Application Layer ❑Please Do Not Tell Sales People Anything

Question 3 –What is a IP Address?

❑Internet Protocol (IP Address) is a 32-bits to 128-bits identifier for a device on TCP/IP protocol. 

❑IP address of a device must be uniquely defined for communication. 

❑And it has two versions which are IPv4 (32-bits) and IPv6 (128-bits).

 

Question 4 – What are the difference between a hub, switch and a router ?

❑ A hub is a basic networking device that connects multiple devices in a LAN but operates at the physical layer (Layer 1).

❑ A switch is a more intelligent device that operates at the data link layer (Layer 2) and uses MAC addresses to forward frames to the appropriate ports.

❑ A router operates at the network layer (Layer 3) and connects different networks, making forwarding decisions based on IP addresses.

 

Question 5 – What is a RJ45 ?

❑RJ45 is the type of the connector used for Ethernet cables.

 

 

Question 6 – By using which command you can trace an IP address 10.1.1.1 on a Router ?

❑traceroute 10.1.1.1 

Question 7 –What is Routing and types of Routing ?

❑ Routing is a process of forwarding packets from one network to another network by selecting best path  & which is performed by a layer 3 i.e network layer devices.

❑ Types of Routing 

❑ 1) Default Routing 

❑ 2) Static Routing 

❑ 3) Dynamic Routing 

Question 8 – What is PING used for?

❑PING is packet Internet groper. 

❑It is used to test the Layer 3 i.e Network Layer reachability of a host on a network. 

 

 

Question 9 – What is the AD Value ?

❑ Administrative Distance AD Value defines the trustworthiness of a routing protocol. 

❑ i.e How reliable the route/s of the routing protocol are !  

❑ Range - <0 - 255>  

Question 10 – What is  AD Value of OSPF?

❑ 110 

AD Values 

❑ Connected interface - 0 

❑ Static route  - 1

❑ External BGP - 20 

❑ EIGRP - 90 

❑ OSPF - 110

❑ RIP - 120 

❑ Internal BGP - 200 

❑ Unknown - 255 (This route is not used)

 

Question 11 – What is the purpose of creating VLANS ?

❑ Broadcast control is the main purpose of creating vlans Other purpose of creating VLANs

❑ VLANs provides Network Security

❑ VLANs provides Segmention

❑ VLANs provides Flexibility - a user can easily move across the physical location and still remain in the same vlan

Question 12 – What is meant by Inter-Vlan Routing ?

❑ VLAN divides the broadcast domains so the hosts can communicate with the other hosts in the same vlan.

❑ When the hosts from one vlans wants to communicate with hosts in other vlan the traffic must be routed between them.

❑ This is known as Inter-Vlan Routing

❑ Inter-Vlan Routing can be achieve either by creating SVI or using Router-on Stick.

 

Question 13 – What is an Autonomous System ?

❑ An Autonomous System (AS) is a group of networks under a single administrative control.

❑ An AS can be Internet Service Provider (ISP) or a large Enterprise Organization.

❑ Each AS will have an ASN

❑ Autonomous System Number (ASN) - 16 bit binary number & we can represent (2^16) numbers, which is equal to 65536 in decimals.

❑ Range of ASN – 0 to 65535

❑ 0 , 65535 - Reserved

❑ 1 – 64511 - Internet Routing – ISP AS

❑ 64512 – 65534 Private Use - Private AS

Question 14 – What is the difference between TCP and UDP?

❑ TCP (Transmission Control Protocol) is a connection-oriented protocol that ensures reliable and ordered delivery of data.

❑ UDP (User Datagram Protocol) is a connectionless protocol that does not guarantee reliable delivery but offers faster transmission. 

❑ TCP is used for applications that require reliable data delivery, while UDP is suitable for real-time applications like streaming and gaming.

Question 15 – What is the purpose of ACLs (Access Control Lists) in networking?

❑ ACLs are used to control and filter traffic based on specified criteria, such as source or destination IP addresses, ports, or protocols.

 

Question 16 – Explain the concept of latency in networking  ?

❑ Latency is the time delay between the transmission of data from the source and its reception at the destination. 

Question 17 – What is ARP?

❑ Address Resolution Protocol (ARP) is a network protocol, which is used to map a network layer protocol address (IP Address) to a data link layer hardware address (MAC Address). 

❑ ARP basically resolves IP address to the corresponding MAC address.  

Question 18 – What is the metric in EIGRP?

❑ Composite Metric.

❑ It don’t consider single criteria to calculate the metric but uses number of criteria which includes Bandwidth , Load , Delay ,Reliability and MTU.

❑ The weightage of these criteria's is defined by something know as K values i.e. Metric Weight. 

❑ By default K values for Bandwidth and Delay are 1 . 

❑ Hence while calculating the metric only Bandwidth and Delay are considered.

Question 19 – What is the metric in OSPF?

❑ Metric is Cost.

❑ Cost depends upon Bandwidth of the link .

❑ Cost is Inversely proportional to the Bandwidth.

❑ Means Greater the Bandwidth less the cost and better the path.

❑ Cost = 100 / Bandwidth (in Mbps)

Question 20 – What is MTU (Maximum Transmission Unit) in a router ?

❑ The maximum transmission unit (MTU) of an interface tells router the largest IP packet that can be forwarded out on that interface. 

Question 21 – What is BGP?

❑Border Gateway Protocol is an Exterior Gateway Routing Protocol which runs between two or more Automous system.

❑ BGP is also known as Routing Protocol of Internet.

 

Question 22 –What is the role of a firewall in networking?

❑ A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between a secure internal network and untrusted external networks.

 

Question 23– What is the purpose of DNS?

❑ DNS (Domain Name System) translates domain names into IP addresses, allowing users to access websites using human readable names instead of numerical IP addresses.

 

Question 24 – What are the port numbers used by Telnet and SSH?

❑ Telnet – 23

❑ SSH - 22

 

 

 

Best of Luck !!!!

 

NES

OSI 7 LAYERS

 The OSI (Open Systems Interconnection) model is a conceptual framework used to understand and describe how different networking protocols and technologies interact with each other. It consists of seven layers, each responsible for specific functions in data communication. These layers, from top to bottom, are:

1. **Application Layer (Layer 7):** This layer interacts with software applications that implement a communicating component. It provides services directly to user applications, enabling network services such as email, file transfer, and remote access.

2. **Presentation Layer (Layer 6):** The presentation layer is responsible for data translation, encryption, compression, and formatting. It ensures that data sent from the application layer of one system can be read by the application layer of another system.

3. **Session Layer (Layer 5):** The session layer establishes, manages, and terminates communication sessions between devices. It controls dialogues (connections) between computers, including synchronization and checkpointing.

4. **Transport Layer (Layer 4):** This layer manages end-to-end communication, ensuring that data packets are delivered error-free, in sequence, and without loss or duplication. It also handles flow control and error checking.

5. **Network Layer (Layer 3):** The network layer is responsible for logical addressing and routing, determining the best path for data to travel from the source to the destination across multiple networks. It deals with IP addresses and performs routing of packets.

6. **Data Link Layer (Layer 2):** This layer provides node-to-node data transfer, framing, error detection, and flow control across a physical link. It ensures that data transmitted between adjacent network nodes is error-free and manages access to the physical media.

7. **Physical Layer (Layer 1):** The physical layer deals with the physical connection between devices. It specifies the hardware requirements for transmitting data on a network, including cables, switches, connectors, and network interface cards (NICs).

Each layer has its own specific functions and protocols that help facilitate communication between different devices across a network. The OSI model serves as a reference point for understanding and designing network systems, allowing different network technologies to work together effectively.

DMVPN

DMVPN (Dynamic Multipoint VPN) is a technique used to build scalable and secure VPNs over the internet or any untrusted network. 

Multicast support within DMVPN is achieved through the use of GRE (Generic Routing Encapsulation) tunnels and protocols like NHRP (Next Hop Resolution Protocol) for dynamic discovery of tunnel endpoints.

Enabling multicast over DMVPN involves additional configurations to support multicast traffic. 

Typically, protocols like PIM (Protocol Independent Multicast) Sparse Mode or Dense Mode are used for multicast routing over the DMVPN network. 

These protocols help in the distribution of multicast traffic efficiently among the tunnel endpoints.

To implement DMVPN with multicast support, you'd typically configure your devices to support multicast routing (using PIM), set up the GRE tunnels between sites, and ensure NHRP is properly functioning to manage the mapping between tunnel IP addresses and physical addresses.

Each site's router participating in the DMVPN network needs to be configured to support multicast routing and have the necessary configurations to ensure that multicast traffic can traverse the tunnels between sites.

To set up DMVPN with multicast support, here are the high-level steps and configuration components:

1. **Basic DMVPN Configuration:**

   - Configure the basic DMVPN setup using GRE tunnels and NHRP for dynamic discovery of tunnel endpoints.

   - Set up the hub and spoke topology, designating a hub router and connecting spoke routers.

2. **Enable Multicast Routing Protocol:**

   - Decide on a multicast routing protocol (PIM Sparse Mode or Dense Mode).

   - Enable multicast routing on the routers:

     - For PIM Sparse Mode:

       - Configure the router to support PIM on the interfaces connected to the DMVPN tunnels.

       - Designate a rendezvous point (RP) for the multicast group.

       - Enable sparse-mode on the tunnel interfaces.

     - For PIM Dense Mode:

       - Enable dense-mode on the tunnel interfaces.

   

3. **Tunnel Configuration:**

   - Ensure that the GRE tunnels support multicast traffic by configuring them appropriately.

   - Assign tunnel source and destination addresses.

   - Enable multicast-specific parameters on the tunnel interfaces, depending on the chosen multicast routing protocol.

4. **NHRP Configuration:**

   - Verify and ensure that NHRP is properly configured to resolve tunnel endpoint mappings.

Here's an example configuration snippet for PIM Sparse Mode on a Cisco router for multicast support over DMVPN:

```markdown

interface Tunnel0

 ip address 192.168.1.1 255.255.255.0

 ip pim sparse-mode

interface Tunnel1

 ip address 192.168.2.1 255.255.255.0

 ip pim sparse-mode

interface <outgoing interface>

 ip pim sparse-mode

ip multicast-routing

ip pim rp-address <RP address>

```

Replace `<outgoing interface>` with the appropriate interface connected to the DMVPN network and `<RP address>` with the actual address of the rendezvous point.

This configuration assumes two tunnels (Tunnel0 and Tunnel1) and enables PIM sparse-mode on those interfaces and the outgoing interface towards the DMVPN network.