Virtual Private Network(VPN)

Do you know? when you search any data on internet it is not secure.All activity that you are doing seen by ISP(Internet Service Provide) and they can track you. So in such situation you need to secure your data.There are several way to secure your data on internet VPN is one of them.

Virtual Private Network is a technology that create a safe and secure or encrypt your data on less secure network such as Internet.VPN technology was developed as a way to allow remote users and offices to securely access data ,applications and other resources.

The information transmitted between the two locations via the encrypted tunnel cannot be read by anyone else because the system contains several elements to secure both the company's private network and the outside network through which the remote user connects through.

The first step to security is usually a firewall between the client and the host server, requiring the remote user to establish an authenticated connection with the firewall. Encryption is also an important component of a secure VPN. Encryption works by having all data sent from one computer encrypted in such a way that only the computer it is sending to can decrypt the data.

Main Protocol Use By VPN

There are three main protocol use with VPN Tunnels.These protocols are generally incompatible with each other. They include the following:

IPSec:-
 A set of protocols developed by the IETF to support secure exchange of packets at the IP layer. IPsec has been deployed widely to implement VPNs. IPsec supports two encryption modes: transport and tunnel.

PPTP:-
The Point-to-Point Tunneling Protocol is a technology for creating VPNs, developed jointly by Microsoft, U.S. Robotics and several remote access vendor companies, known collectively as the PPTP Forum.

L2TP:-
Layer Two (2) Tunneling Protocol is an extension to the PPP protocol that enables ISPs to operate Virtual Private Networks (VPNs).

Technical Interview Questions asked in Top Companies

Q.1:- How will you implement Linked list with 1 million nodes? How will you access 999999th node?

Q.2:- Clone a linked list with next and random pointer.

Q.3:-Serialise and Deserialise a linked list with next and random pointer.

Q.4:-Given two sorted array(with repetitive elements) find kth minimum number from both array.

Q.5:-Given two linked list both represent a number.Create a linked list that create its sum.

Q.6:-Given a binary search tree, print the path which has sum equal to k and has minimum hopes.i.e. if there are multiple paths with the sum equal to k then print the path with minimum number of nodes.

Q.7:-Given an array, arrange the elements such that the number formed by concatenating the elements is highest. 
E.g.: input = [9, 93, 24, 6], the output should be: [9,93,6,24]. This is because if you concatenate all the numbers, 993624 is the highest number that can be formed.     

Q.8:-Given an string find the longest sub string which is palindrome.  

Q.9:-How would you create your own hash function?

Q.10:-How would you implement red-black tree?

Q.11:-Tell me what you think about Google Charging users $1 per month to use Gmail.

Queue in Java

Queue is FIFO(First In First Out) data structure.In which every element insert in the rear end and deleted from front end.
Some method which very helpful during coding on the basis of Queue is following-

boolean offer(Object obj):- This method is used for insert an obj in the rear end of the Queue.If insertion of obj is successful it return true else false.

Object poll():- This method return head(first) element of Queue and also delete it.If no element exist in the Queue it return null.

Object remove():- This method also return head(first) element of Queue and delete it But when no element found in the Queue it return NoSuchElementException.

Object peek():-  This method return head(first) element of Queue but It does not delete it and return null when Queue is Empty.

Object element():- This method also return head(first) element of Queue and does not delete it but when Queue is Empty it return NoSuchElementException.

add() method is also use for insert element in the rear end of the Queue.

Best Questions ask by Google in Job Interviews

Question1:How would I explain the importance of HTML 5 to Larry Page and then to my grandma?

Question2: How could you solve humankind's biggest crisis given $1 billion and a spacecraft?

Question3: Let’s say you have to construct Google maps from scratch and guide a person standing on Gateway of India (Mumbai) to India Gate (Delhi). How do you do the same?

Question4: Estimate the number of students who are college seniors, attend four-year schools, and graduate with a job in the United States every year.

Question5: If you had access to a bank's database, how would you use that information to design an ATM for elderly people?

Question6: How would you solve homelessness in downtown San Francisco?

Question7: A man pushed his car to a hotel and lost his fortune. What happened?

Question8: Anywhere in the world, where would you open up a new Google office and how would you figure out compensation for all the employees at this new office?

Question9: Design an evacuation plan for the building.

Question10: A coin was flipped 1,000 times and there were 560 heads. Do you think the coin is biased.

Question11: What is your opinion on whether or not individuals should be required to use their official name when opening a Gmail or Google + account?

Question12: You’re the captain of a pirate ship, and your crew gets to vote on how the gold is divided up. If fewer than half of the pirates agree with you, you die. How do you recommend apportioning the gold in such a way that you get a good share of the booty, but still survive?

Question13: How many ways can you think of to find a needle in a haystack? Asked in an interview in May 2014

Question14: If you could only choose one song to play every time you walked into a room for the rest of your life, what would it be?

Question15: What’s 2 to the power of 64?

Question16: How many times a day does a clock’s hands overlap?

Question17: What is the probability of breaking a stick into 3 pieces and forming a triangle?

Question18: Tell me what you think about Google charging users $1 per month to use Gmail. This question was asked in an interview in 2015

Question19: How many haircuts do you think happen in America every year?

Dynamic Programming

Dynamic programming like divide and conquer method , solves problems by combining the solutions to sub-problems.
Divide-and-Conquer algorithms partition the problem into disjoint sub-problems , solve the sub- problem recursively and then combine their solutions  to solve original problem.
In contrast dynamic programming applies when the sub-problem  overlap that is when sub-problem share sub-problem

Feature of Dynamic programing

1)Optimal Substructure
2)Overlapping Sub-Problems

Optimal Substructure

A given problem has optimal substructure property if optimal solution of the given problem can be obtained by using optimal solutions of its sub-problems.
For example :-The shortest path problem has the following optimal substructure property.If a node x lies in the shortest path from node u to node v then the shortest path from u to x and shortest path from from x to v. The standard all pair shortest path algorithm like Floyd Warshall and Bellman-Ford typical example of dynamic programming.

Overlapping Subproblem

Like divide and conquer, Dynamic programming combine solutions to sub-problems.Dynamic programming is mainly used when solution of same sub-problems are needed again and again. In dynamic programming, computed solutions to sub-problems are stored in a table so that these don't have recomputed. So dynamic programming is not used when there are no common(overlapping) sub-problems.

How to add Contact On Gmail

We know that no one can not remember the contact number of everyone and if we have not our phone then we need a technology that store our contact number and when we need it can show.Google service Gmail is one of them.
Let's know how we can add contact number on gmail and see anytime.Follow the steps.

Step1:- Login to your Gmail account.

Step2:- Click on Contact icon which show right side in the up corner.

Step3:- Click on plus(+) icon which show left side in down corner.

Step4:- Fill the contact information like name,email,phone number etc. and click on the save button.

Now your contact information is save on gmail contact.You can see it any time remotely.

Navigational Satellite

Navigational Satellite is a group of satellite that provide geographical location of object on the earth.It is also used to find the rout or destination address of the object,show the rout of ships and airplane and if anyone forget there rout then through navigational satellite we can find them.Google map is work on the basis of navigational satellite GPS(Global Positioning System).
Now a days only four country USA,RUSSIA,EUROPEAN UNION and CHINA`have their own navigational satellite.But INDIA have also launch their own navigation satellite and very soon it will work.
Navigational satellite and their country name is following

1)NAVSTAR Global Positioning System (GPS)  -USA  32 medium earth orbit satellites operations since 1978
 
2) GLONASS - Russian since 1995 

3) Galilio - European Union - 30 MEO satelites some are  operations since 2014 , expected to be in full service till 2020 
 
4)Beidou-2  - China  , 30 MEO satellites , expanding current regional service into global by 2020

5)IRNSS- INDIA, It is set of eight satellite IRNSS1A,IRNSS1B,IRNSS1C,IRNSS1D,IRNSS1E,IRNSS1F,IRNSS1G,IRNSS1I

Internet of things (IOT)

Collection of all devices which are connected to the internet are called internet of thing.
For Example: Mobile Phone,Security Camera,Smart Cars,Router,Smart houses ,Cofee makers, Washing Machine,Headphone,wearable devices etc.These devices can communicate between or other and also can share their information.
These all devices are very beneficial to human life because these are work automaticaly. For example if you have a smart car that have GPS(Global Positioning System) and it is connected to internet and you go anywhere and suddenly something happened then your car will help you to call somebody.
 

Top 15 Engineering College in India 2018 NIRF Report

NIRF(National Institute Ranking Framework) issue ranking of engineering colleges in which there are many IIT and NIT are top position.So let's know ranking of the engineering colleges.

Rank 1:Indian Institute of Technology, Madras

Number of Faculty Member with Ph.D Qualification=606
Total no. of Faculty Member=607
Number of Women Faculty Member=78

 

Rank 2:Indian Institute of Technology,Bombay

Number of Faculty Member with Ph.D Qualification=527
Total no. of Faculty Member=528
Number of Women Faculty Member=61

 

Rank 3:Indian Institute of Technology,Delhi

Number of Faculty Member with Ph.D Qualification=476
Total no. of Faculty Member=481
Number of Women Faculty Member=73

 

Rank 4:Indian Institute of Technology,Kharagpur

Number of Faculty Member with Ph.D Qualification=641
Total no. of Faculty Member=644
Number of Women Faculty Member=66

 

Rank 5:Indian Institute of Technology,kanpur

Number of Faculty Member with Ph.D Qualification=418
Total no. of Faculty Member=418
Number of Women Faculty Member=34

 

Rank 6:Indian Institute of Technology,Roorkee

Number of Faculty Member with Ph.D Qualification=419
Total no. of Faculty Member=423
Number of Women Faculty Member=51

 

Rank 7:Indian Institute of Technology,Guwahati

Number of Faculty Member with Ph.D Qualification=388
Total no. of Faculty Member=401
Number of Women Faculty Member=41

 

Rank 8:Anna University,Chennai

Number of Faculty Member with Ph.D Qualification=581
Total no. of Faculty Member=903
Number of Women Faculty Member=401

 

Rank 9:Indian Institute of Technology,Hyderabad

Number of Faculty Member with Ph.D Qualification=181
Total no. of Faculty Member=183
Number of Women Faculty Member=21

Rank 10:Institute of Chemical Technology,Mumbai

Number of Faculty Member with Ph.D Qualification=108
Total no. of Faculty Member=116
Number of Women Faculty Member=38

 

Rank 11:National Institute of Technology Tiruchirappalli

Number of Faculty Member with Ph.D Qualification=243
Total no. of Faculty Member=346
Number of Women Faculty Member=113

 

Rank 12:Jadavpur University,Kolkata

Number of Faculty Member with Ph.D Qualification=287
Total no. of Faculty Member=323
Number of Women Faculty Member=65

 

Rank 13:Indian Institute of Technology,Dhanbad

Number of Faculty Member with Ph.D Qualification=311
Total no. of Faculty Member=340
Number of Women Faculty Member=22

 

Rank 14:Indian Institute of Technology,Indore

Number of Faculty Member with Ph.D Qualification=116
Total no. of Faculty Member=116
Number of Women Faculty Member=13

 

Rank 15:National Institute of Technology Rourkela

Number of Faculty Member with Ph.D Qualification=278
Total no. of Faculty Member=299
Number of Women Faculty Member=42

 

10 facts you should know to improve your phone battery life

Lower your phone's screen brightness/set this to automatic

Let your phone automatically decide its optimum screen brightness according to the ambient environment. In case you want a manual control over its brightness, it's advisable you set it close to the 50 per cent mark, rather than keeping it to a full. Your smartphone's bright and vibrant display consumes a lot of power, therefore keeping a check on it should improve battery life significantly.

Turn off Bluetooth and Wi-Fi when you don't need them

It's a common sight for users to keep their Bluetooth and/or Wi-Fi on for far longer than they need them. Sometimes, you share a file via Bluetooth and then forget to close it. As for the Wi-Fi, many users have it open to detect available connections and connect accordingly. An open Bluetooth and Wi-Fi are significant power drainers on your phone since they continuously work to detect nearby signals. Also, keeping these open unnecessarily is also a threat to your smartphone privacy/security.

Keep a check on your location/GPS Tracking

Similar to your Bluetooth and Wi-Fi functions, the location tracking feature that tracks your location using radio waves and satellites (Google Maps is an example) drains out your phone battery drastically. It is recommended that you keep this on only when you require navigation, and keep it close at all other times (to keep a check on your mobile data as also its battery).

Keep your screen timeout low

Screen timeout is the time your smartphone takes to automatically go into a sleep mode in the absence of any activity (swipe or tap). Keep the screen timeout of your phone to a minimum. After all, keeping your display on when you don't need it is a genuine waste of battery juice.

Turn off notifications from unnecessary apps

While it's good to receive notifications from useful apps (like news and email etc), most apps today tend to send out random notifications that are really not needed. Take for instance, notifications from games like Asphalt that ask you to play it for you've been away from the race track for a while now. Seriously, do you really need that?

Also, it's advisable to have the phone vibrate function off for notifications (also in general) to save on your battery juice since vibration drains it significantly.

Multitasking is good, but close apps when you're done with them

With more and more phones having greater RAM memory on-board, multi-tasking is what you call a walk in the park for a majority of the handsets. While multi-tasking is good, it is also a battery hog. Keep useful apps (that you'd generally open) in the background while closing all unnecessary apps to free your RAM as also keep your battery life in check. You can always open an app when you need it.

Avoid using flash while taking photos

Smartphones today include an LED flash along with the cameras (heck some even include flash for the front camera). While an LED flash is a handy resource in low light, it is also a major battery drainer. Use it only if you must, and use it wisely.

Don't let your phone heat up unnecessarily

Today we are getting phones that have powerful hardware inside a sleek frame. Therefore, heating is a common phenomenon in most of these handsets. Heating takes excess toll on your device's battery life. While you cannot totally control what's going on inside your smartphone, you can at least keep a check on your phone's ambient environment. This means, avoid keeping your smartphone in direct sunlight or even your pockets for that matter (especially during summers).

Don't wait for your phone to discharge completely before charging

Many users think it's wise to drain the battery completely before charging it fresh. Well, it's time to smell coffee in that case. Most phones come with Lithium Ion batteries and in the case of Li-ion batteries, draining them completely before charging them again may lead to lowering your battery life or even damaging them in some cases. It's advisable you keep charging your phone occasionally, instead of waiting for it to drain out completely.

Keep a portable charger at hand

It's always handy to keep an additional power source with you should your phone run out of juice at the most unfortunate of times. Portable chargers or power banks are useful devices and the market is flooded with some really good ones today (at affordable prices too).