Component of the browser:

1. User Interface

2. Browser Engine

3. Rendering Engine

4. Networking

5. JavaScript Interpreter

6. Ui backend

   

   The user Interface is the where when you open the browser you see.In the User Interface you will , the address bar, back.forward button, bookmark menu and tab which we all interract with it.The Browser engine is the core of the browser .it facilates the communication between the other component of the browser.it provide the resource to the Render enginer for rendering the webpage.In the Networking component , it handle all the networking communication.it send http request to the server , receive the http response and make connection between the user and server.when the server send the webpage rsources , first it comes to the browser engine , its gets to rendering engine .The rendering engine contains the html and css parser where it parse the html and css , and make the corresponding dom .after the dom of html and css is made then it goes to the frame constructor ,which help in making the frames after then it goes to the frame/reflow tree, In this it do calculation like shaping or sizing the frame or coloring etc at it do the painting .as the user interact ,it interact with javascript interpreter as well.

Before there is tranfer of data between client and server .The tcp do three way handshake.In general the client send the tcp segment which contains the synchronize sequence number to the server , then server send sement which contains both the syn no and the acknowledgement no to the client. agian the client send the acknowledgement on . if both the syn no and acknowledge no match from the both client and server side, then connection is established else connection is rejected .Now lets discuss in detail about it with the help of diagram

There are two host P and Q.The host P send the seq ‘X‘ to host q , for the acknowledgement host Q send its own seq no ‘Y‘ and ACK no =X+1.again the host P send the ack no =Y+1 which is received by the HOST Q.

Tcp and Udp are protocol used in the transport layer of osi model which is at layer 4.Tcp is connection oriented protocol which first make connection between the client and the server .break the data in the segment and hand over the segment to the ip protocal , from there ip route the segement to the correct destination .udp is connectionless protocal because it does not make connection between the client and the server. it just send data to the destination address.

2.Key differences between TCP and UDP

Tcp

-connecection oriented protocal

-reliable and ordered data delivery

-higher overhead but high accuracy

Udp:

-connectionless and lightweight

-no guarantee of order or delevery

-low overhead and high speed

3.When to use TCP

we use tcp when want the accurate data in the right order. for eg sending the email.

4.When to use UDP

we use the udp when we dont want accurate data and right order but want at high speed.eg:video conferencing

5.What is HTTP and where it fits

HTTP(hypertext transfer protocal) work at the application layer. whenever we send the request, it goes from applocation layer,in the transport layer the tcp and udp comes in the picture

It is a command line tool which is used to transfer data and from the server.The most common use case is Api request.

2.Why programmers need cURL

mainly programmer use this to test the api end point .it is working as expect or not so that it can be fixed.

3.Making your first request using cURL

i tried curl https://anjanpajiyar.com command , this command returned me the html of the website.

cURL is made from four parts i.e endpoint,http method , header, body.The endpoint is the address(url ) which we are sending the request.the common http method are get ,post ,put and delete.the get http request is used to retrieve a resource from the server.the post http request is used send the resource to the server.the put http request is to used create or update the resource in the database of the server.the delete http request is used to delete a resource from the database of the server..the header contains the metadata about the request like the content-type and user-agent etc.the body is used with put and post as we are sending the information so .

• dns is domain name system which means if you give name of the website , it will return the ip address of the website .

2.Why DNS records are needed

-the dns record is much important , as it store the instruction and tells us how we can reach the particular server. without dns record ,the internet would be impossible.

3.whats an NS record is ?

-Ns record is the server which stores information about the domain.the authorative dns have the address of the ns where the record is stored.

4.what is a A record is?

-A record is one of the fundamental type of record found in the name server which contain IPV4 address.

5.What an AAAA Record is?

-AAAA record com contain only the IPV6 address .if any request comes to to AAAA record then it send the IPV6 address.

6.What a CNAME Record is?

-cname is the type of dns record which is alis of another domain .for example , blog.anjanpajiyar is the alias of anjanpajiyar

7.What an MX Record is?

-the MX record know the where the mail server and help in the routing.when you send message it goes to mail transer agent(MTA) to find the mail server and follows the smtp

8.What a TXT Record is?

The txt record is both human readable and machine readable. it store about general detail about the domain and it store the verification details

Modem(modulator and demodulator):

-The main function of modem is to covert digital data to analog signal and vice-versa

-the modem is found just before the isp(internet service provider) .

-suppose you searched https://anjanpajiyar.com ,the first request goes router which just routes the path , after that it sends to the modem which convert the digital data like 0s,1s into the analog signal after that analog signal travel in internet through cable or telephone line or optical fibers, after that it goes to modem nearest to the the website domain , which again convert into digial data as computer only understand the digital data .

Router:

-The function of the router is to connect different computer network and manage the traffic .

-the router is the only network device which helps connection in LAN and WAN,

-the difference between the router and the modem is that the router connect the device,manage traffic while the modem help in converting the signal

Hub:

switch is the network device which work on multicasting , when any one computer send the information to the switch,then the send this information to all other computer. the problem with this is collision happens if the multiple sender send the information.instead of sending information to only destination computer, its sending to all , there is wastage of bandwith.

Switch:

-it is mainly used in the lans and wans to connects the computer and forwarding data to destination computer

-the switch get source mac address and destination mac address,so it is used to send to particular mac address

Firewall:

-the firewall is present between the internet and your network.

-firewall montor the request, if the request is good then it will give the acess to enter to my network else acess will be denied.

-firewall save us from the hackers

Load-balancer:

-The function of the load balancer is to distribute the load across the server.

-as we know that if the traffic is high then the single server cant handle all the requestion , as it crashes.but the server should be available 24 hours so solution of that problem is load balancer

DNS-domain name system

Resolution-finding the solution of the problem

So basically ,Any device in the internet to communicate with each other, we need IP(intenet protocal) address.The example of ip address is 198.51.100.10.just ask a question to yourself , memorizing number is easy or the name .if there is large number of devices , it becomes difficult to memorize the ip address.so its better to memorize the domain name .so the solution of problem is dns resolution.if you give domain name to dns Resolver then the dns Resolver gives you the ip address . once your browser gets the ip address , it can request corresponding web pages.

so we understood the purpose of the dns , now lets understand in detail.

so There are 4 server involved in dns resolution:

1.recursive server:

whenever we search any website in the browser then , this request goes to the recursive server which send of you the ip address of the website . the recursive job request to multiple server to find the ip address. the first request goes to the root server while the last request goes to the authoritative server/

2.root server:

this server returns the adress of tld server like .com,.org etc . based on what request it came to us , address of that tld only.

3.TLD server:

so the recursive server request to tld for ip of the domain name but it return the address NS of domain name.

4.authoritative server:

This is the only server who know the address of the website , it return the ip address to the recursive servive which then return to the browser.

mainly git has three main stage that is working tree , staging area and the local repository. whatever you work upon it stages on the working tree . as you do git add , it will create git object for each file . then you do git commit then , for each commit , it will be creating a tree object , which connect the current bob object and the previous tree . and the git commit connect with current git object and teh previous commit

2. Understanding the .git Folder

.git is the git tracking folder which is used to store the changes on the repository

this is how the .git folder looks like.

3. Git Objects: Blob, Tree, Commit

to understand the git objects in the simple terms, we will go though pratically. so will start with the first command git int .

this means the git repository is initialized. now lets check what inside the .git

we can clearly see the bunch of file and folders. you might have noticed that there there is objects/ , this is the same topic what we are studying .so now lets see what is inside the objects/ folder.

we can clearly see that inside the objects/ , there is info/ and pack/ folder, but the info and pack folder was empty .so now lets create some file and add some content on it .

i have created the demo1 file and added the content on it . so now lets the move the file to staging area from the unstaged area and do commit.

so after commiting , you can see that it is displayed 1 file changed and 1 insertion(+).so it is temporarly stored in local repository . hope you all know what is repository , if you dont know then google-search or refer to my previous blogs , you can understand. now lets check the same object folder inside the .git file .

you can clearly see the three new folder has been added.now lets open the 03 folder and check what is inside inside it

found the hash value of 38 character.

the command is git cat-file -t <hash value> .actually total number of charcter in hashvalue , the first two character is used for folder naming and the remaining is used as reference value which is used to store something.we found that the file type of this hashvalue is bob .the bob is one of the git object that we are trying to understand.now lets checks value of this hash value.

git cat-file -p <hash value> it is used display the content of the hashvalue ,acutally the hashvalue is the address which used to store something . we got the content called hello geeks the same content we store in the file demo1.txt.it is ovious the bob object is used store the changes made in your local repository.now lets check the file type and content of two other folder which we found.

by running the command we found the file type as tree which is git object.inside this object we found

tree object basically store the bob object(with hash value with file name).

last folder type is commit which is the git object.its check that what inside it.

the commit object store the tree object , author and committer.again i created another file demo2.txt

note": in the stage area only the bob object is created while when the file move from the staging area to the local repository the tree and commit object is created.

due to above two command more three folder is created for git object like bob , tree and commit.

you may be confused with git cat-file -p 350f2e5c49e2c93cff2f2f62f4e6c15e94ee24c7 ,actutally it is tree whole is storing two bob object , i will explain with the diagram

the tree 1 is created when we did the first commit and tree 2 in second commit .whenever we do anycommit then curent tracked file which is stored in new tree along with all prevous tree is linked with it.the red colured text represent the hash value of that.

now let me explain the relatioship between the bob, tree and commit object with the help of the diagram

as you can see the for each commit it as own tree with its bob object and every commit is linked with the previous commit so it can be tracked easily

4. How Git Tracks Changes

when you create some file or folder and add content on it and then you run the command git add <file-name> ,internally it will create the hash value and out of 40 character of hash value , the first two will the file name and the remaining 38 character can be be found inside the folder which start with two charater hash value.so inside the 38 charater hash value file .so it create the git object file .so if you run command git commit -m “message“ , it will create both git tree and git commit . for each git commit , it have corresponding tree with its bob objects .git uses hashes to ensure the integrity , if there is any change in repository so as the result the hash changes

Git is the open source distributed version control system .version control system is the software which tracks the changes to code in file over time .version control system is of two types :

1. centralized version control system (cvcs):

In the centralized version control system , there is a single server where every member of the team synchronize with the server to get updated code , if any member of the team changes the code or add feature then it has to be updated in server so that other member can synchronize with it.If the central server goes offline then no one can synchronize with central server . it is good for small team but not ideal for the large.

note: synchronize means the codes of all member of the team should be same

2. ** distributed version control system:**

In the distributed version control system ,every member has the local copy of the remote repository , if anyone want to makes changes or add new feature then they do in the local repository , then it has to be pushed in the remote repository so that other member can pull the updated code and synchronize with other.so there no dependency of sigle server

note:repository means the storage where all your project files, code and tracking history file.the local repository is stored on local computer while remote repository is store on cloud based server.

the git solves the problem of the tracking of the changes in the codes.git was created by the Linus Torvalds in April 7, 2005..the difference between the git and github is that the git track the changes in the code in project file while github is use to host the git due to which collabration and synchronize was possible.who should learn git in this 21st centuary .the answer anyone who is working with digital files especially in the collaborative environment should learn git

Why git

we need to understand the problems people faced before Git .They are

1. **Complete project history of channges: ** without git, its was very hard to track the changes in the code , you could not easily see what as added , what was removed , when it changed. if this is difficulty for one person ,it becomes much more frustating ehrn many people are working on same project

Git Core Terminologies

1. Repository (Repo):storage area where the project file and git file

2. Working Directory: the folder in your computer where you work on the project

3. Staging Area (Index):It is the temporary storage area before saving in the local repositories.

4. Commit:it saves the changes from staging area to the local repositories

5. Branch:its is the workspace where you make some changes and try new idea without affecting the project

   

6. Merge:it is used to merge one or more branch into another

7. Clone: it is process of creating the duplicate copy from the remote orginal project

8. Pull:it is used fetch the remote repository , if there is changes then it is used to integrate into the loal repository.

9. Push:integrating the changes done into local repository into the remote repository.

10. Remote:Remote is also called as the remote reposotory.which means which is hosted on the internet.

11. HEAD:It the address pointer which store address of the current commit.

12. Status:It display the current status of the working directory and the staging area.

13. Log: it display the all list of commit in the repository.

14. .gitignore:it is the special file in the git which tells the system which file or folder to ignore while commiting

15. Checkout:it is used to create new branch and switch between the branches

    common git command

    1. git init

    2. git log

    3. git add <file>

    4. git status

    5. git commit -m ‘message‘

    6. git clone <url>

    7. git checkout <branch name>