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Ans. Single instance means there is only 1 instance that will bear all the traffic load whereas Load balanced server means that there will be a cluster of servers that will host the application and load will be balanced distributed among them. Auto Scaling means that the number of instances will be expanded / shrunken based on the rule. Rule could be the traffic count , response time etc.
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Ans. Load Balancing is a provision to improve performance by reducing load on a single machine / server. Traffic or load is distributed among different machines and hence resulting in better performance / response time by leveraging more resources.
Failover is a provision to achieve better availability by switching to a backup server in case of failure.
Load Balancing aims as improving performance whereas failover aims at improving availability.
We can achieve both together by using a Load Balancing system which will isolate an instance in case of it's failure.
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LikeDiscussCorrect / Improve  load balancing  failover  load balancing vs failover  production support
Ans. Conversion means that the expression / literal / value of one type getting converted to other type.
Widening conversion is the conversion from Type A to Type B where B requires a wider space than A. For example - int to long, float to double, char to String etc. As the value moves to a wider space, there is no loss of information.
Narrowing conversion is the conversion from Type A to Type B where B requires a narrower space space than A. For example - int to long, float to double, char to String etc.As the value moves to a narrower space, there is a loss of information.
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Ans. Amazon CloudWatch is a monitoring service for AWS cloud resources like Beanstalk and DB instances. We can use CloudWatch to monitor the state of resources, collect metrices, set alarms and appropriate response to the alarm state.
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Ans. Latency is the delay incurred while communicating a message i.e the time took the message in transit over network.
processing time is the delay it took for the server to process the request.
Response time is the sum total of latency and processing time.
For example -
Let's say it takes 1 ms for the request to reach from client to server and similar 1 ms for the response to come back to client. Moreover it takes approx 10 ms for the application to process the request. So The response time would be outward latency + processing time + inward latency = 12 ms
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Ans. Amazon Elastic Compute Cloud or EC2 provides scalable computing capacity in the AWS cloud. It can be used to create Virtual Environments , storage and configure. EC2 enables to upgrade or downgrade infrastructure according to the rules defined ( with fluctuation in latency, traffic etc )
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Ans. Games are very good examples of threading.You can use multiple objects in games like cars, motor bikes, animals, people etc. All these objects are nothing but just threads that run your game application.
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Ans. There is no specific order in which database fires the triggers if they are for the same operation. If we need to have a specific order for their execution, we should have them all in a stored procedure and the procedure should get executed upon the event.
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Ans. It's an operating system file that maps IP address to host names. The hosts file assists the OS in addressing networked components and serves the function of translating human friendly hostnames into numeric protocol addresses, called IP addresses, that identify and locate a host in an IP network.
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Ans. Though var args are used rarely but they are pretty useful if a method is expected to receive variable number of arguments. For example - it's pretty useful for the main method as the caller has the flexibility to provide arguments in infinite ways.It provides a convenience and flexibility to the caller.
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Ans. Yes, it will give compilation error and java will complain about duplicate method. Java treat var args internally as arrays and hence would result in same byte code for both method's syntax.
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