3. What is a Firewall?
A firewall is a network security device that monitors incoming and outgoing network traffic and
decides whether to allow or block specific traffic based on a defined set of security rules.
Firewalls have been a first line of defense in network security for over 25 years. They establish a
barrier between secured and controlled internal networks that can be trusted and untrusted
outside networks, such as the Internet.
A firewall can be hardware, software, or both.
4. What is DNS?
Domain Name Server (DNS) is a standard protocol that helps Internet users discover websites
using human readable addresses. Like a phonebook which lets you look up the name of a person
and discover their number, DNS lets you type the address of a website and automatically discover
the Internet Protocol (IP) address for that website.
Without DNS, the Internet would collapse - it would be impossible for people and machines to
access Internet servers via the friendly URLs they have come to know.
For example, the domain name www.exampleweb.com you are viewing now, translates to the IP
address 104.20.48.182 (in the old IPv4 format) or 2002:6814:30b6:0:0:0:0:0 (in the newer IPv6
format).
5. What is the difference between a Domain and a
Workgroup?
Domain : Domain is a client/server network where user can login from any device of the office. Also
known as Remote login. It has a centralized administration and all devices can be managed from a
centralized device. It prefers a centralized storage and all the users data is stored at a centralized
storage device which can be NAS or SAN.
Workgroup : Workgroup is a peer to peer windows computer network, where users can use his login
credentials only on his or her system and not others. It holds an distributed administration
wherein each user can manage his machine independently. Most storage is distributed. Each device
has its own dedicated storage.
6. What is a Proxy Server and how do they protect
the computer network?
A proxy server acts as a gateway between you and the internet. It’s an intermediary server
separating end users from the websites they browse. Proxy servers provide varying levels of
functionality, security, and privacy depending on your use case, needs, or company policy.
Proxy servers act as a firewall and web filter, provide shared network connections, and cache data
to speed up common requests. A good proxy server keeps users and the internal network
protected from the bad stuff that lives out in the wild internet. Lastly, proxy servers can provide a
high level of privacy.
7. What are IP classes and how can you identify
the IP class of given an IP address?
IP addressing is the most popular way to identify a device on the network. The address has 32 bits
which can be broken into four octets(1 octet=8 bit). These octets provide an addressing method
through which we can accommodate large and small networks. Accordingly, there are 5 classes of
the network
Class A Class B Class C Class D Class E
from 10.0.0.0 to
10.255.255.255.
Used by large
private networks,
such as a
multinational.
from 172.16.0.0 to
172.31.255.255.
Used by medium-
sized networks,
such as an SME or
a study center.
192.168.0.0 to
192.168.255.255.
Used by medium
networks, such as
home.
Class D has IP
address range
from 224.0.0.0 to
239.255.255.255.
Class D is
reserved for
Multicasting
Reserved for
future use, or
research and
development
purposes.,IP
addresses in this
class ranges from
240.0.0.0 to
255.255.255.254.
Like Class D
8. What is meant by 127.0.0.1 and localhost?
When you call an IP address on your computer, you try to contact another computer on the
internet but when you call the IP address 127.0.0.1 then you are communicating with the localhost.
Localhost is always your own computer.
Localhost is always your own computer. Your computer is talking to itself when you call the
localhost. Your computer not always directly identifies the local host. Within your personal
network localhost has a separate IP address like 192.168.0.1.(for most cases) which is different to
the one you use on the internet. This is usually dynamically assigned by the internet service
provider (ISP). Localhost can be seen as a server that is used on your own computer.
9. What is NIC?
A network interface card (NIC) is a hardware component, typically a circuit board or chip,
which is installed on a computer so that it can connect to a network. Modern NICs provide
functionality to computers such as support for I/O interrupt, direct memory access (DMA)
interfaces, data transmission, network traffic engineering and partitioning
A NIC provides a computer with a dedicated, full-time connection to a network by
implementing the physical layer circuitry necessary for communicating with a data link layer
standard, such as Ethernet or Wi-Fi
10. What is Data Encapsulation?
Data Encapsulation is an Object Oriented Programming concept that
bind a group of related properties, functions, and other members are
treated as a single unit. Class is the best example of Data
Encapsulation. It sometimes referred to as data hiding that prevents
the user to access the implementation details. Encapsulation
therefore guarantees the integrity of the data contained in the
Object.
11. What is the difference between the Internet,
Intranet, and Extranet?
Internet: The Internet is a global interconnection of computer systems. It is a massive collection of
networks sharing information publicly in the form of interlinked web pages. IP or Internet Protocol
defines a site’s unique location on the World Wide Web.
Intranet: An intranet network is only accessible to a small group of people. Intranets are mainly used
within businesses and organizations to provide access to files and applications on networked
computers and servers. Intranets are sometimes defined as a private Internet.
Extranet: An extranet is comparable to an intranet, but is accessible via a Web portal. An intranet
resides behind a firewall, and is accessible only to people who are members of the same group,
company or organization. Extranets are becoming a very popular means for business partners to
exchange information securely.
