# Networking Interview Questions for Experienced

Suppose there are 4 routers. How many connections do we need to connect these routers in a fully meshed topology?

To count the total required number of connections in a fully meshed topology, the following formula is used.

```Total required number of connections = N*(N-1)
```

Here N is the total number of devices.

For 4 routers we need, 4*(4-1) = 12 connections.

What is the difference between a server and a dedicated server?

A dedicated server is also a server but it is deployed to provide a specific service. For example, if a server is providing all regular services in the network then it is considered a server. But if it is providing only a specific service such as a web server that provides only web service and nothing else then it is considered a dedicated server.

Based on the application access, what are the differences between the Internet, Intranet, and Extranet?

On the Internet, anyone can access the application from anywhere in the world.

On the Intranet, only the authorized users from the company for which the application was built can access the application.

On the Extranet, selected external users can access the application which is built for the Intranet.

How does a ring topology network work?

In a ring topology network, all computers connect in a circle. When a computer has some data packets for another computer, it puts them in the circle. Each computer looks at each packet to figure out whether the packet is intended for it or not. If the packet is intended for it, it will process the packet, otherwise, it will ignore the packet.

In a bus topology network, a loose terminator detaches from the coaxial cable and leaves it open at one end. Will this network work as expected?

No, this network will not work. In a bus topology, both ends of the cable must be terminated.

In a star topology network, a cable that was not properly attached to the hub is accidentally pulled out from the hub. Will this network work?

Yes, only the device which was connected with that cable will lose connectivity. The remaining devices work normally.

In a star topology network, Due to fluctuation in light, a centralized hub is burnt. Although all connected devices and cables are unaffected, will these devices be able to access the network?

No, in a star topology network, if the centralized hub is failed, all devices will lose connectivity.

Does the number of computers matter in LAN and WAN?

No, the number of computers does not matter in LAN and WAN. This categorization is purely based on the geographical location of the network. For example, we may have 1000 computers connected to a network. If this network is located in a building or on campus, it will be considered a LAN network. Just like this, we may have a network of only two computers. If one computer is located in one city and another computer is located in another city then this network will be considered a WAN network.

What are some popular IEEE standards?

The following table lists some popular IEEE standards.

 Standard Description 802.1 Standards for LAN/MAN bridging and management 802.2 Standards for Logical Link Control (LLC) 802.3 Ethernet Standards CSMA/CD 802.4 Standards for Token passing bus access 802.5 Standards for token ring access and communications between LANs and MANs 802.6 Standards for information exchange between systems 802.7 Standards for broadband LAN cabling 802.8 Standards for Fiber optical connection 802.9 Standards for integrated services, like voice and data 802.10 Standards for LAN/MAN security implementations 802.11 Standards for WiFi (Wireless Networking) 802.12 Standards for demand priority access method 802.14 Standards for cable television broadband communications 802.15 Standards for Bluetooth network 802.15 Standards for ZigBee (Wireless Sensor/Control Networks) 802.16 Standards for WiMAX Wireless Networking

What is a firewall?

A firewall is a networking device or an application software that, based on preconfigured rules, filters the data which passes through it. There are two types of firewall: hardware firewall and software firewall.

What are the differences between a hardware firewall and a software firewall?

A hardware firewall is installed on a device that is specially made for it. Since the firewall is integrated at the hardware level and uses all processing power and memory of the device, it is extremely fast in comparison to a software firewall. On the negative side, it is too expensive and complex.

A software firewall is installed as an add-on application on the host OS. On the negative side, it is quite slow and less effective in comparison to a hardware firewall. On the positive side, it is less expensive. Some open-source firewalls are available even free of cost.

What is the difference between the operating system and application software?

The operating system is the main program while application software is an add-on program. The operating system installs on the computer and accesses system resources such as CPU, RAM, and Hard disk directly. While application software installs on the operating system and accesses system resources through the operating system.

What is the Kerberos?

Kerberos is an authentication mechanism developed by the Massachusetts Institute of Technology. It uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.

What is the difference between the Half-Duplex mode and Full-Duplex mode?

In the half-duplex mode, a NIC can either send or receive data at a time. While in the full-duplex mode, it can perform both operations simultaneously.

What is an anonymous FTP account?

An anonymous FTP account is a special FTP account that allows guest users to access the FTP server anonymously.

What is a computer bus?

A computer bus is a logical system that allows multiple peripherals or components to connect with the system through a single wire or a cable. A computer bus can be categorized based on how it transmits the data and where it is used.

Based on data transmission, there are two types of buses: the parallel bus and the serial bus. On the parallel bus, several bits of data are transmitted at the same time. While, on the serial bus, only a single bit of data is transmitted at a time.

Based on the location of usage, again there are two types of the bus: internal bus and external bus. Internal buses are used to transfer the data between internal components. Internal components are the components that are either integrated or installed on the motherboard such as CPU and RAM.

External buses are used to transfer the data between internal components and peripherals. Peripherals are the devices that connect with the motherboard through the cables such as Hard disks and DVD Writer.

Why a Straight-through UTP cable cannot be used to connect two systems directly?

In a straight-through cable, pins are arranged in the same order at both ends. A system uses pins 1 and 2 for the sending data and pins 3 and 6 for the receiving data.

If we use a straight-through cable to connect two systems, pins 1, 2, 3, and 6 of one system will connect with pins 1, 2, 3, and 6 of another system. Since, instead of connecting to the receiving pins, sending pins are connected to the sending pins, the data transmission will be failed. For a successful data transmission, the sending pins must be connected to the receiving pins. For this reason, to connect two systems directly, a cross cable is used.

A cross cable connects the sending pins to the receiving pins.

Which addresses are reserved in IPv4?

In IPv4, the following addresses are reserved and cannot be assigned to end devices.

• 0.0.0.0:- This address represents all networks.
• 127.0.0.0 to 127.255.255.255: - This IP range is reserved for loopback testing.
• 224.0.0.0 to 239.255.255.255 (Class D): - This IP class is reserved for multicast.
• 240.0.0.0 to 255.255.255.254 (Class E): - This IP class is reserved for future use.
• 255.255.255.255: - This address represents all hosts.

What is a Trojan horse?

A Trojan horse is a malicious code that is hidden in a legitimate application. It is used by hackers to gain unauthorized access to the system and once access is gained, to steal sensitive information from the system.

What is a virus?

A is a small malicious computer program that is designed to damage the system and annoy the users. Usually, it hides in another program and travels with that program. When that program is installed, it is also installed with that program on the system.

What is an antivirus?

An antivirus is a program that is used to scan and eliminate malicious programs from the stored data and installed applications.

How is a cross-over cable made?

In a cross-over cable, the pins sending data from one end are connected to the pins receiving data at the other end. Pins 1 and 2 (sending pins) respectively connect to pins 3 and pin 6 (receiving pins).

What is the network relationship type?

The term network relationship type defines how the nodes communicate with each other on the network. There are two types of network relationships: peer-to-peer and server/client.

In the peer-to-peer network relationship, all nodes are treated equally. Any node can share its resources in the network and can access any shared resource from the network. In this type of relationship, data is stored on each node individually.

In the client/server network relationship, all nodes are treated based on their roles on the network. The server node has the highest privilege. It shares resources and information on the network. Client nodes have less privilege. They access the shared resources from the server. In this type of relationship, usually, data is stored on the server system only.