What are protocols? TCP/IP
and UDP protocol explained with examples in detail.
ANSWER
Protocols
are sets of rules and instructions that computers use to communicate with each
other. It is a standardized method of information transfer between devices.
Transmission
Control Protocol/ Internet Protocol (TCP/IP)are two different procedures that
are often linked together. TCPoperates at the Transport layer. Its
function is to provide connection-oriented services and perform segment
sequencing and service addressing. It also performs important error-checking
functions and is considered a host-to-host protocol. SSH, FTP, telnet andSMTP
are examples of TCP.
On the other hand, Internet Protocol (IP) is the main TCP/IP
protocol. It is a connectionless protocol that makes routing path decisions,
based on the information it receives from ARP (Address Routing Protocol). It
also handles logical addressing issues through the use of IP addresses. The
linking of these protocols is common since the functions of different protocols
can be complementary so that together they can carry out some tasks completely.
In fact, the term "TCP/IP" is normally used to refer to a whole suite
of protocols, each with different functions. This suite of protocols is what
carries out the basic operations of the Web. IPv4, IPv6 and IPsec are examples
of IP.
When information is sent over the Internet, it is generally
broken up into smaller pieces or "packets". The use of packets
facilitates speedy transmission since different parts of a message can be sent
by different routes and then reassembled at the destination. IP is the method
used to route these messages to the proper address while TCP is the means for
creating the packets, putting them back together in the correct order at the
end, and checking to make sure that no packets got lost in transmission. If
necessary, TCP will request that a packet be resent.
User Datagram Protocol (UDP) is a protocol used together
with IP when small amounts of information are involved. It is simpler than TCP
and lacks the flow-control and error-recovery functions of TCP. Thus, it uses
fewer system resources.User Datagram Protocol (UDP) is considered a
host-to-host protocol like TCP. It also performs functions at the Transport
layer. However, it is not connection-oriented like TCP. Because of less
overhead, it transfers data faster, but is not as reliable.TFTP, SNMP and IP
are examples of UDP.
Proxy and their uses
ANSWER
Proxy (server) is a cache memory for
internet web pages accessed. A proxy is an intermediate server or a buffer
between a computer accessing the internet and internet being accessed to
provide administrative control and security. The proxy server make sure that
the file(s) frequently accessed by millions of users on the network everyday
are stored or saved for easier access in case another user or same
user may
make such request another time. That is, the cache of a proxy server may
beforehand have all the information before the time of your request and
transports the information instantly once the request is made again. Therefore
the quick reply made possible by proxy server ensures speedy internet
connectivity.
Besides that the proxy server can by
itself server as firewall, accepting and denying requests made by the clients
as well as ensuring security. This is done by anonymous proxy server. What
anonymous proxy does is that it hides or conceals your IP address and any of
your informationto avoid unpermitted or unofficial access to a user through the
internet. For this reason, it could be called a secure gateway to the user.
Uses of Proxy Server
Request filtering: Proxy servers are also used in
request filtering. Due to some privacy reasons, an organization may have to
deny their users or personnel access to a particular website. Proxy server
makes this possible for the organization.
Web Document Caching: Proxy makes a document caching of a
frequently visited sites. That is, it saves frequently visited sites into a
memory named “cache”. This makes the access to that same site/file easier for
another user when requested. For instance, user A visited a particular site.
Two days later, user B accessed the same site. When user A first visited the
site, the files accessed were saved in a cache memory. Now, user B will have a
quicker access to the same site due to the fact that his request no longer have
to be furthered to the web server.
Detects Intruders:As intruders may intend to hack or gain
administrative access to a user’s account via net, proxy halts that request. So
as a firewall, a proxy prevents unauthorized access to a user via online.
What is IEEE standard?
ANSWER
Institute
of Electrical Electronics Engineering (IEEE) standardcomprises a family
of networking standards that cover the physical layer specifications of
technologies from Ethernet to wireless.It is a collection of networks which
includes CSMA/CD, token ring, and token bus. Some of the standards are as follows:
·
802.1:The
main function is bridging. It works in
making sure that LAN/MAN are bridged and managed. Covers management and the
lower sub-layers of OSI Layer 2 (Data Link Layer), including MAC-based address
bridging (Media Access Control), virtual LANs and port-based access control.
·
802.2: Commonly called the “Logical Link
Control (LLC)”. It is the top sub-layer in the OSI Layer 2 (Data Link Layer).
·
802.3: This
is called the Ethernet.It provides asynchronous networking using "carrier
sense, multiple access with collision detect" (CSMA/CD) over coax,
twisted-pair copper, and fiber media. It runs at a speed of 10Mb/s to 10Gb/s.
·
802.4:
Token bus
·
802.5: This
is as well called the IBM token ring. It is the original token-passing standard
for twisted-pair, shielded copper cables. Supports copper and fiber cabling
from 4Mb/s to 100 Mb/s.
·
802.11: This
is known as the Wifi.It is a local
area wireless computer networking technology that allows electronic devices to
network, mainly using the 2.4 gigahertz (12 cm) UHF and 5 gigahertz
(6 cm) SHFISM radio bands. Many devices can use Wi-Fi, e.g. personal
computers, video-game consoles, smartphones, digital cameras, tablet computers
and digital audio players. It can connect to a network resource such as the
Internet via a wireless network access point. Such an access point (or hotspot)
has a range of about 20 meters (66 feet) indoors and a greater range outdoors.
Hotspot coverage can be as small as a single room with walls that block radio
waves, or as large as many square kilometers achieved by using multiple
overlapping access points.
·
802.12: This
is a mechanism that defines a different MAC mechanism for transmitting network
frames.
·
802.15.1:
Is the basis for the Bluetooth wireless communication technology
·
802.15.4: This is known as ZigBee. It is a low
tier, ad hoc, terrestrial, wireless standard in some ways similarto Bluetooth.
·
802.15.6:
Meant for Wireless Body Area Network.
·
802.21: This
is a standard designed for interoperability between 802 and non 802 networks.
·
802.22: This
is a standard for Wireless Regional Area Network.
Explain NAT in detail
ANSWER
Network
Address Translation (NAT) is a technology used in translating and mapping
public IP address (provided by internet service provider) to private IP
address(Local IP address on the LAN network ) and private IP to public IP. When
NAT is configured on the network, all the local users on the LAN will have
access to internet resources. With the use of NAT private IP address could also
be mapped with private IP. NAT also increases home network security by
confining the access of external computers into the home IP network space. It
is a common technology in internet connection sharing.
It is
configured or established on gateway devices like routers, on the network
boundary. It can also be applied on software. Sometimes it is built in server
load balancing applications on corporate networks. It does not offer all
properties of a true firewall. The “software” is mainly run in servers that
have other antiviruses and firewall. Let me explain the types of NAT.
·
Static NAT:This is a type of NAT a private IP
address is mapped to a public IP address. That is, for each private IP address
there is a public IP address. The public IP address here has a fixed private IP
address. This lets an internal host like the web server to have an unregistered
IP address and yet is accessible over the internet. Due to the “one public
IP-one private IP”nature of Static NAT, it is called a one-to-one network translation. It is mostly useful when a
particular network device needs to be accessible from outside the network.
·
Dynamic NAT:This is a type of NAT in which a
pulled public IP is mapped to a private IP on the network. In the NAT router on
the network is a pool of public IP addresses. So when a private IP makes a
request to access the internet, the router selects an unassigned public IP and
gives it to the public IP making the request. When this process is completed,
it is saved in the NAT table. This type of NAT is mostly applicable where a
whole IP subnet will share a group of public IP addresses.
·
NAT overload or Port Address
Translation: This
type of NAT maps multiple private IP to one public IP. All computers on the
private network are translated to the same public IP except for different port
number assignment.
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