Technical interview questions and answers are critical when preparing for an AJAX Interview because companies want to evaluate your understanding of asynchronous communication, XMLHttpRequest, JSON handling, DOM manipulation, and interactive web applications. AJAX is considered a core concept in modern web development, and many companies include it as part of their technical rounds for frontend and full-stack developer roles. Organizations like TCS, Infosys, Wipro, Cognizant, and Capgemini frequently ask AJAX-related questions to check whether candidates can build dynamic, responsive, and efficient web pages. This guide includes commonly asked AJAX interview questions with clear explanations to help freshers and job seekers strengthen their web development fundamentals. These questions will improve your preparation for placement interviews, coding rounds, and real-time project discussions.
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81. From a versioning perspective, what are the drawbacks of extending an interface as opposed to extending a class?
With regard to versioning, interfaces are less flexible than classes. With a class, you can ship version 1 and then, in version 2, decide to add another method. As long as the method is not abstract (i.e., as long as you provide a default implementation of the method), any existing derived classes continue to function with no changes. Because interfaces do not support implementation inheritance, this same pattern does not hold for interfaces. Adding a method to an interface is like adding an abs
82. Which one is trusted and which one is untrusted?
Windows Authentication is trusted because the username and password are checked with the Active Directory, the SQL Server authentication is untrusted, since SQL Server is the only verifier participating in the transaction
83. What namespaces are necessary to create a localized application?
System.Globalization, System.Resources.
84. Does Console.WriteLine() stop printing when it reaches a NULL character within a string?
Strings are not null terminated in the runtime, so embedded nulls are allowed. Console.WriteLine() and all similar methods continue until the end of the string.
85. What is the advantage of using System.Text.StringBuilder over System.String?
StringBuilder is more efficient in the cases, where a lot of manipulation is done to the text. Strings are immutable, so each time it is being operated on, a new instance is created.
86. What are advantages and disadvantages of Microsoft-provided data provider classes in ADO.NET?
SQLServer.NET data provider is high-speed and robust, but requires SQL Server license purchased from Microsoft. OLE-DB.NET is universal for accessing other sources, like Oracle, DB2, Microsoft Access and Informix, but it is a .NET layer on top of OLE layer, so not the fastest thing in the world. ODBC.NET is a deprecated layer provided for backward compatibility to ODBC engines.
87. Why do I get a security exception when I try to run my C# app?
Some security exceptions are thrown if you are working on a network share. There are some parts of the frameworks that will not run if being run off a share (roaming profile, mapped drives, etc.). To see if this is what's happening, just move the executable over to your local drive and see if it runs without the exceptions. One of the common exceptions thrown under these conditions is
System.Security.SecurityException.
To get around this, you can change your security policy for the intranet zo
88. What is the difference between // comments, /* */ comments and /// comments?
Single-line, multi-line and XML documentation comments.
89. How do you inherit from a class in C#?
Place a colon and then the name of the base class. Notice that it is double colon in C++.
90. Can I define a type that is an alias of another type (like typedef in C++)?
Not exactly. You can create an alias within a single file with the "using" directive: using System; using Integer = System.Int32; // alias
But you can't create a true alias, one that extends beyond the file in which it is declared. Refer to the C# spec for more info on the 'using' statement's scope.