chapter2 Flashcards
network application
network application are those application which connect diff devices on the globe
an network applicatin must work on diff end explain
also explaion why we can not write code for network core
1) write a prog which can run on diff end system i.e host and server
2)note : we do not need to write code to run this application on network core i.e routers etc because they function on lower layer rather then application layer
are the netwrok arch diff from the application arch
yes very diff
two important type of application arch is
client-server archt and peer to peer archt(p2p)
what is client server arch and what is ment by data center in this arch
in this arch we have a host called as server and a client here the host give service to client requests the host have unique adddress called ip address when the clint want to contact the host so he will be using the ip adddress the host is always running and the client can not cumminacate with other client like twp web pages or two web brwoser can not interfare each other
well data center can be defind as a set of large number of servers which cumminate with very large number of hosts ,
we need data center beacsue a one single server can not handle large number of requests from the clinet
google has 19 data center
peer to peer arch , benefit , drawback
here the arch do not need server here the directly cumminate with other host called peer these peer are in the desktop mobile etc controlled by user
example is file sharing applications
benfit are scaleblity and cost effective as we do not need server so no bedwith
drawbask are challenges of security, performance, and reliability due to their highly
decentralized structure.
proccess cumminacting def , proccess inside the same end system, process cummin outside of end sys, and how they cumminate outside of endsystem
an application running on end system is called process
the proccees running in the end system can be refer as programme also and they cumminate by interprocess cumminate
a process outside the end system can cumminate by exchanging the messages across computer network
process is just a way of exchanging messages
Client and Server Processes def and detail
in the netwrok application we have two types of arch i.e client server here the clinet broweser send messsage to serevr by browser proccess so called clinet process and the server respond to the request by server process called server process
in p2p the clinet server is those that dowlload the data and serevr process is that uplaod the file or data
note in p2p the same divice can be both client and server process
define socket and how does it help in proceesing the messges
the process send or recove the messages from a network through software interface called socket this socket can be represented as the door of house and the house is a process so if process want to send a message it must use door and from door by cumminaciting path this message will reach to other door i.e socket and the finally house called process
s shown in this figure, a socket
is the interface between the application layer and the transport layer within a host
remeber it
a socket is also known as Application Programming Interface (API) why ?
because the socket is interface between the application layer and the network layer
addressing process what is it and why we need
in seding emai we need the destination address called the addressing process , we can also send packet from one host to other but we must know about the destination host address
what is ip addresss, and what is port number why we need port number
ip is defind as the unique 32 bit address of a host
port number is which help us in remembering sending the porcess and also in recinvign the process
a web server is identifd by 80 port number
services of transport layer protocol that gives to application are 4 name them
relaible data transfer, throuput , timing and security
one service of transport layer is reliable data transfer what is it?
reliable data transfer mean when there is no loos of data from one end to other end system
one service of transport layer is throughput what is it?
throughput means the rate at which a sending porcess send messge to the reciver porcess it is r bits/sec
here the layer must proovide an throughput that is constant that is no matter what happen but the throught put can not be less then Rbits/sec
those divice which can not operate below a spefic throuput are called bendwith-sensative application
name two trasnport protocol provoded by internet is
tcp and udp
TCP is a transport protocol provoded by internet and it have connection orineted services and reliable data transfer what does it means
connection orineted xservices: this means before the exchanging of data the server and cleint are already alert to stay prepare for data this is called hand shakking
relaible data transfer : this means no loos of data
UDP servces
it is lightwaight it is connectioless so no handshaking before data and also no relaible data transfer
application layer protocol ?
application layer protocol defines how an application process and it gives follwing services
1)type of messages exchanged i.e recving and sending
2)syntax of messages
3) meaning of messages
4) when and how to respond a message
web browser use HTTP application layer protocl
all short detail about HTTP , how messages are send va HTTP, why HTTP is called statless protocol
HTTP is application layer prorcol uses by web application
HTTP is installed on both server and client end system so thus the cleint and server both cumminate via HTTP protocol
in sending messages the clint brwoser(chromm) send request via an interface that is a door by http and then tcp takes that messages and reach this to sever door i.e interface and then server http take this message and respomd it since we are using tcp so we are sure that no looos of data
http is also called statless protocol becasue on the server side the server do not rembebr the client infor like if a client reqeust an image and if he request again so server will respond again becasue server do not know that the cleint already requested the image
non persistent and persistent connection ?
non persistent : those connection where the sending and recing pear of messages take place on diff tcp
persistent : take place on single tcp
RTT or rount trip time meaning
which is the time it takes for a small packet to travel from client to server
and then back to the client. The RTT includes packet-propagation delays, packet-
queuing delays in intermediate routers and switches, and packet-processing delays
what is cookies and how many componen it have
cookies are used to keep track of users
they have 4 major component
1) cookie headler line in http which recive message
2)cookie headler line in http which send message
3)cookie file kept in user end system browser
4) a backend database kept in server
web cache is also called proxy server what is web cache and why we use it
web cache is also called a proxy sever beacuse it has it is own local disk which keeps copies of recently requested obj
for example if i want an obj so my browser will send http request to web cache if the obj is present so web cache will respond otherwise the web cache will request the obj form origin serevr make a copy in its own local disk and then rspond to the request
conditional get used in cache
this request is used when the cache want to know the obj inside cache is modified or not
the request look like this
An HTTP request message is a so-called conditional GET message if
(1) the request message uses the GET method and (2) the request message includes an
If-Modified-Since: header line.
why we use ip address
ip address are used for routers because we humen can not remember the ip addre of each site and if we use the name so routers can not process it
so this reason fr humen we have names like www.google.com and for router we have its ip address
brief intro of ip address
ip address consist of 4 bytes and it has hierarchical structure
. All DNS query and reply mes-
sages are sent within UDP datagrams to port 53.
. All DNS query and reply mes-
sages are sent within UDP datagrams to port 53.
what is centrlized dns design and there problem
a centrliezed design is system that dns has only one server and all mapping are done there
they have prob like as below
1)if dns crash so whole internet fails because it is one and sigle dns
2)one dns so allot of traffic
3)one dns so alot of distence from some pionts
4)lot of maintance are required
