Answer:- There are mainly two security affecting factors: • Unauthorized Access • Viruses

Answer:- The following factors affect the reliability of a network: • Frequency of failure • Recovery time of a network after a failure

Answer:- The following factors affect the performance of a network: • Large number of users • Transmission medium types • Hardware • Software

Answer:- There are mainly two criteria which make a network effective and efficient: • Performance: : performance can be measured in many ways like transmit time and response time. • Reliability: reliability is measured by frequency of failure. • Robustness: robustness specifies the quality or condition of being strong and in good condition. • Security: It specifies how to protect data from unauthorized access and viruses.

Answer:- Every signal has a limit of upper range frequency and lower range frequency. The range of limit of network between its upper and lower frequency is called bandwidth.

Answer:- A network is a connection setup of two or more computers directly connected by some physical mediums like optical fiber or coaxial cable. This physical medium of connection is known as a link, and the computers that it is connected are known as nodes.

Answer:- A node that is connected to two or more networks is commonly known as a gateway. It is also known as a router. It is used to forward messages from one network to another. Both the gateway and router regulate the traffic in the network. • Differences between gateway and router: A router sends the data between two similar networks while gateway sends the data between two dissimilar networks.

Answer:- DNS is an acronym stands for Domain Name System. • DNS was introduced by Paul Mockapetris and Jon Postel in 1983. • It is a naming system for all the resources over the internet which includes physical nodes and applications. It is used to locate to resource easily over a network. • DNS is an internet which maps the domain names to their associated IP addresses. • Without DNS, users must know the IP address of the web page that you wanted to access. Working of DNS: If you want to visit the website of "javaTpoint", then the user will type "https://www.javatpoint.com" into the address bar of the web browser. Once the domain name is entered, then the domain name system will translate the domain name into the IP address which can be easily interpreted by the computer. Using the IP address, the computer can locate the web page requested by the user.

Answer:- • A forwarder is used with DNS server when it receives DNS queries that cannot be resolved quickly. So it forwards those requests to external DNS servers for resolution. • A DNS server which is configured as a forwarder will behave differently than the DNS server which is not configured as a forwarder. • Following are the ways that the DNS server behaves when it is configured as a forwarder: • When the DNS server receives the query, then it resolves the query by using a cache. • If the DNS server is not able to resolve the query, then it forwards the query to another DNS server. • If the forwarder is not available, then it will try to resolve the query by using root hint.

Answer:- • NIC stands for Network Interface Card. It is a peripheral card attached to the PC to connect to a network. Every NIC has its own MAC address that identifies the PC on the network. • It provides a wireless connection to a local area network. • NICs were mainly used in desktop computers.

Answer:- It is used to specify data transfer rate. In 10Base-T, 10 specify the data transfer rate, i.e., 10Mbps. The word Base specifies the baseband as opposed to broadband. T specifies the type of the cable which is a twisted pair.

Answer:- • NOS stands for Network Operating System. It is specialized software which is used to provide network connectivity to a computer to make communication possible with other computers and connected devices. • NOS is the software which allows the device to communicate, share files with other devices. • The first network operating system was Novel NetWare released in 1983. Some other examples of NOS are Windows 2000, Windows XP, Linux, etc.

Answer:- Networks can be divided on the basis of area of distribution. For example: • PAN (Personal Area Network): Its range limit is up to 10 meters. It is created for personal use. Generally, personal devices are connected to this network. For example computers, telephones, fax, printers, etc. • LAN (Local Area Network): It is used for a small geographical location like office, hospital, school, etc. • HAN (House Area Network): It is actually a LAN that is used within a house and used to connect homely devices like personal computers, phones, printers, etc. • CAN (Campus Area Network): It is a connection of devices within a campus area which links to other departments of the organization within the same campus. • MAN (Metropolitan Area Network): It is used to connect the devices which span to large cities like metropolitan cities over a wide geographical area. • WAN (Wide Area Network): It is used over a wide geographical location that may range to connect cities and countries. • GAN (Global Area Network): It uses satellites to connect devices over global are.

Answer:- POP3 stands for Post Office Protocol version3. POP is responsible for accessing the mail service on a client machine. POP3 works on two models such as Delete mode and Keep mode.