HTTP tunneling is used to encapsulate other protocols within
the HTTP or HTTPS protocols. It is typically used to pass
protocols that would normally be blocked by a firewall
through the firewall in a controlled manner.

There are two types HTTP tunneling 
 1.HTTP to Port

 2.Http To CGI
 
  this concept is frequently used in RMI

http is a hyper text transfer protocol
it is used in web server to web client
it is a one kind of internet protocoils

This well-worn method is popular since it requires almost 
no setup, and works quite well in firewalled environments 
which permit you to handle HTTP through a proxy, but 
disallow regular outbound TCP connections. 
If Java RMI fails to make a normal (or SOCKS) connection to 
the intended server, and it notices that a HTTP proxy 
server is configured, it will attempt to tunnel Java RMI 
requests through that proxy server, one at a time. 

There are two forms of HTTP tunnelling, tried in order. The 
first is http-to-port; the second is http-to-cgi. 

In http-to-port tunneling, Java RMI attempts a HTTP POST 
request to a http: URL directed at the exact hostname and 
port number of the target server. The HTTP request contains 
a single Java RMI request. If the HTTP proxy accepts this 
URL, it will forward the POST request to the listening Java 
RMI server, which will recognize the request and unwrap it. 
The result of the call is wrapped in a HTTP reply, which is 
returned through the same proxy. 

Often, HTTP proxies will refuse to proxy requests to 
unusual port numbers. In this case, Java RMI will fall back 
to http-to-cgi tunneling. The Java RMI request is 
encapsulated in a HTTP POST request as before, but the 
request URL is of the form http://hostname:80/cgi-bin/java-
rmi.cgi?port=n (where hostname and n are the hostname and 
port number of the intended server). There must be a HTTP 
server listening on port 80 on the server host, which will 
run the java-rmi.cgi script (supplied with the JDK), which 
will in turn forward the request to a Java RMI server 
listening on port n. Java RMI can unwrap a HTTP-tunneled 
request without help from a http server, CGI script, or any 
other external entity. So, if the client's HTTP proxy can 
connect directly to the server's port, then you don't need 
a java-rmi.cgi script at all. 

To trigger the use of HTTP tunneling, the standard system 
property http.proxyHost must be set to the hostname of the 
local HTTP proxy. (There are reports that some Navigator 
versions do not set this property.) 

The major disadvantage of HTTP tunneling is that it does 
not permit inward calls or multiplexed connections. A 
secondary disadvantage is that the http-to-cgi method opens 
a dramatic security hole on the server side, since without 
modification it will redirect any incoming request to any 
port

HTTP 1.1's connection keep-alive feature allows the TCP
connection between a browser and a Web server to remain open
throughout multiple HTTP requests and responses. This
significantly improves the overall performance of
browser-server communication.

Http operates on what is called a request-response 
paradigm. This means that a _client_ generates a request 
for information, and passes it to the server, which answers 
it. In the original implementation of HTTP, each request 
created a new socket connection to the server, sent the 
request, then read from that connection to get the response.

This approach had one big advantage - it was simple. Simple 
to describe, simple to understand, and simple to code. It 
also had one big disadvantage - it was slow. So, keep-alive 
connections were invented for HTTP. 

HTTP/1.0
Under HTTP 1.0, there is no official specification for how 
keepalive operates. It was, in essence, tacked on to an 
existing protocol. If the browser supports keep-alive, it 
adds an additional header to the request: 

Connection: Keep-Alive

Then, when the server receives this request and generates a 
response, it also adds a header to the response:

Connection: Keep-Alive

Following this, the connection is NOT dropped, but is 
instead kept open. When the client sends another request, 
it uses the same connection. This will continue until 
either the client or the server decides that the 
conversation is over, and one of them drops the connection.

HTTP/1.1
Under HTTP 1.1, the official keepalive method is different. 
All connections are kept alive, unless stated otherwise 
with the following header:

Connection: close

The Connection: Keep-Alive header no longer has any meaning 
because of this.

Additionally, an optional Keep-Alive: header is described, 
but is so underspecified as to be meaningless. Avoid it.

Port is that which transfers data from one computer to 
another via a cable that links connecting ports.

Its nothing but logical address
that is 0 to 1023, these are resrved for servers
remaining 1024 to 65535 are clients

A port is a connector for attaching cables, for example: 
Parallel port is used for connecting printer with system 
and Serial port is used for connecting monitor with CPU.

On computer and telecommunication devices, a port is 
generally a specific place for being physically connected 
to some other device, usually with a socket and plug of 
some kind.
 In programming, a port is a "logical connection place" and 
specifically, using the Internet's protocol, TCP/IP, the 
way a client program specifies a particular server program 
on a computer in a network.

Port is that which transfers data from one computer to 
another via a cable that links connecting ports.

Preemptive multitasking also called "time slicing". 
Interrupting the execution of a process and passing control 
to another waiting process and performing a context switch 
after which the context for the next pending process is 
restored, and the next process is executed for the duration
of its time slice or "quantum".

Preemptive multitasking also called "time slicing". 
Interrupting the execution of a process and passing control 
to another waiting process and performing a context switch 
after which the context for the next pending process is 
restored, and the next process is executed for the duration
of its time slice or "quantum".

Preemptive multitasking also called "time slicing". 
Interrupting the execution of a process and passing control 
to another waiting process and performing a context switch 
after which the context for the next pending process is 
restored, and the next process is executed for the duration
of its time slice or "quantum".

Preemptive multitasking also called "time slicing". 
Interrupting the execution of a process and passing control 
to another waiting process and performing a context switch 
after which the context for the next pending process is 
restored, and the next process is executed for the duration
of its time slice or "quantum".

I tis an object in java compiler. Used to 
manipulate/identify the InternetAddress(IP Address) of 
local system or remote system.

InetAddress is a class in java by which we can get IP 
address of any machine.
method is "public static InetAddress getLocalHost()"

An identifier for a computer or device on a TCP/IP network.

 Networks using the TCP/IP protocol route messages based on 
the IP address of the destination. The format of an IP 
address is a 32-bit numeric address written as four numbers 
separated by periods. Each number can be zero to 255. For 
example, 1.160.10.240 could be an IP address. 
Within an isolated network, you can assign IP addresses at 
random as long as each one is unique. However, connecting a 
private network to the Internet requires using registered 
IP addresses (called Internet addresses) to avoid 
duplicates. 

The four numbers in an IP address are used in different 
ways to identify a particular network and a host on that 
network. Four regional Internet registries -- ARIN, RIPE 
NCC, LACNIC and APNIC -- assign Internet addresses from the 
following three classes. 

Class A - supports 16 million hosts on each of 126 networks 
Class B - supports 65,000 hosts on each of 16,000 networks 
Class C - supports 254 hosts on each of 2 million networks 
The number of unassigned Internet addresses is running out, 
so a new classless scheme called CIDR is gradually 
replacing the system based on classes A, B, and C and is 
tied to adoption of IPv6.

IP address is a unique address for a host to connect in a 
network.IP has two types.one is private add another is 
public add.
it represent 32 bit binary number.it has two name part one 
is anetwork part another is host part.ip add. network part 
is fixed part and host part is unique part.an ip -add. 
controled by IANA-INTERNET ASSIGN NUMBER OF AUTHORITY.
An ip add. is normaly expressed in decimal format.

Every IP multicast group has a group address. IP multicast 
provides only open groups: That is, it is not necessary to 
be a member of a group in order to send datagrams to the 
group. 

Multicast address are like IP addresses used for single 
hosts, and is written in the same way: A.B.C.D. Multicast 
addresses will never clash with host addresses because a 
portion of the IP address space is specifically reserved 
for multicast. 

This reserved range consists of addresses from 224.0.0.0 to 
239.255.255.255. However, the multicast addresses from 
224.0.0.0 to 224.0.0.255 are reserved for multicast routing 
information; Application programs should use multicast 
addresses outside this range.

The difference is that TCP is responsible for the data 
delivery of a packet and IP is responsible for the logical 
addressing. 

In other words, IP obtains the address and TCP guarantees 
delivery of data to that address.

Tcp is transfer contorl protocol,tcp is responsible for 
delivery of data packets and ip is for logical addressing .

we can say Ip obtain the correct address and TCP gurantees 
delivery of data to taha particular address.

TCP is a protocol based on a connection between two 
computers. It is used for normal Internet traffic and 
applications such as web servers, FTP, etc.

UDP is a protocol based on connectionless communication. 

UDP is ideal for applications like video streaming and 
online gaming, where lost packets don't need to bre 
retransmitted and speed takes precedence.

TCP/IP is a two-way communication between the client and the
server and it is a reliable and there is a confirmation
regarding reaching the message to the destination.it is like
a phone call.
  UDP is a one-way communication only between the client and
the server and it is not a reliable and there is no
confirmation regarding reaching the message to the
destination. it is like a postal mail.

tcp/ip protocol is reliable one .The acknoledgement is 
maintained here.Loss of data can be regained with the help 
of acknowledgement.Udp protocol is unreliable no 
acknowlwdgement is mainted here mainly speed factor plays a 
dominet role. No regain of lost data takes place

TCP is a Transmission Control Protocol. 
UDP is a User Datagram Protocol.
There are four major differences between UDP and TCP:
1. TCP can establishes a Connection and UDP cannot.
2. TCP provides a stream of unlimited length, UDP sends 
small packets.
3.TCP gurantees that as long as you have a connection data 
sent will arrive at the destination, UDP provides not 
guarantee delivery.
4.UDP is faster for sending small amounts of data since no 
connection setup is required, the data can be sent in less 
time then it takes for TCP to establish a connection.

TCP is a connection oriented protocol, which means that 
everytime a packet is sent say from host A to B, we will 
get an acknowledgement. Whereas UDP on the other hand, is a 
connection less protocol.
Where will it be used : TCP -> Say you have a file transfer 
and you need to ensure that the file reaches intact, and 
time is not a factor, in such a case we can use TCP.

For more details : http://newadmins.blogspot.com/

TCP is a Transmission Control Protocol. 
UDP is a User Datagram Protocol.
TCP protocol is mainly used when we need report that our
data has trasferred succesfully or not,
while UDP doesnot check

1.	TCP(Transmission Control Protocol). TCP is a 
connection-oriented protocol, a connection can be made from 
client to server, and from then on any data can be sent 
along that connection. 
o	Reliable - when you send a message along a TCP 
socket, you know it will get there unless the connection 
fails completely. If it gets lost along the way, the server 
will re-request the lost part. This means complete 
integrity, things don't get corrupted. 
o	Ordered - if you send two messages along a 
connection, one after the other, you know the first message 
will get there first. You don't have to worry about data 
arriving in the wrong order. 
o	Heavyweight - when the low level parts of the 
TCP "stream" arrive in the wrong order, resend requests 
have to be sent, and all the out of sequence parts have to 
be put back together, so requires a bit of work to piece 
together. 
2.	UDP(User Datagram Protocol). A simpler message-
based connectionless protocol. With UDP you send messages
(packets) across the network in chunks. 
o	Unreliable - When you send a message, you don't 
know if it'll get there, it could get lost on the way. 
o	Not ordered - If you send two messages out, you 
don't know what order they'll arrive in. 
o	Lightweight - No ordering of messages, no tracking 
connections, etc. It's just fire and forget! This means 
it's a lot quicker, and the network card / OS have to do 
very little work to translate the data back from the 
packets.

1.tcp is connection oriented udp is connectionless
tcp is reliable udp is not;

TCP is Tranmission Control Protocol

IP - Internet Address

UDP - User Datagram Protocol.

transmission control protocal

internet protocal

user diadram protocal

TCP is transmission control protocol
IP internet protocol
UDP user diagram protocal

TCP Transmission Control Protocol
IP  Internet Protocol
UDP User Datagram Protocol

It is a class in Java which represents an Internet Protocol
(IP) address. An instance of an InetAddress consists of an
IP address and possibly corresponding host name

TCP:its a protocal for transfering data that is reliable 
and commonly used.
IP:Internet Protocl
UDP:its unreliable but fast mode of transfering data.

TCP-transmission control protocol
IP-Internet protocol
UDP-unreliable control protocol

URL means Universal Resource Locator

URL stands for Uniform Resource Locator and it points to
resource files on the Internet.
  URL has four components.
http://www.allinterview.com:80/index.html
http - protocol name,
allinterview - IP address or host name,
80 - port number,
index.html - file

url is a uniform or universal resource locator(An Internet
World Wide Web Address.)...which is used to find the web
pages....It includes the protocol, the domain and the name
of the file.

Uniform Resource Locator, the global address of documents
and other resources on the World Wide Web.

Inet address is one of identifier. This is used denote the 
IP address of the networked system.

Every computer connected to a network has an IP address.An
IP address is a number that uniquely identifies each
computer on the Net.An IP address is a 32-bit number.

Inet address identifies the IP address of any system
conneted to the network ,and this identifier is used in java
,and it  is something similar  to datatypes in c  and c++ .

It is mensioned the system address

InetAddress is a class used to find the ip address of a host
in a network.

This InetAddress is divided into two types,
1)Inet4address for the ip version 4(ipv4)=Which has 32bit ip
address
2)Inet6address for the ip version 6(ipv6)=Which has 128bit
ip address

There are subclasses & abstract in the InetAddress.

An Internet Protocol (IP) address is a numerical label for
devices  used  in a computer network. An IP address serves
two principal functions in networking: host identification
and location addressing.it is 32 bit for ip version 4 and
128 bit forip version 6.

Inet address is a class encapsulating both this ip address
and the domain name for this address.This class can be used
for getting the ip address of systems by providing the name
and vice versa.This is done by some functions in the class
such as getaddress(),getbyname()

DNS stands for Domain Name System, an Internet service that 
translates domain names into IP addressess. Because domain 
names are alphabetic, they're easier to remember.  The 
Internet however, is really based on IP addresses.  Every 
time you use a domain name, therefore a DNS service must 
translate the name into the corresponding IP address. For 
example, the domain name www.sudheer.com might translate to 
192.168.252.101.

It is very difficult to remember a set of numbers(IP
address) to connect to the Internet.The Domain Naming
Service(DNS) is used to overcome this problem.It maps one
particular IP address to a string of characters.
  FOr example, www.allinterview.com implies com is the
domain name reserved for commercial sites,allinterview is
the name of  the company and www is the name of the specific
computer,which is allinterview's server.