ServiceNow Interview Questions, Process, and Tips

Shell in Linux is a command-line interpreter that allows users to interact with the operating system by executing commands.

• Shell is a program that takes commands from the keyboard and gives them to the operating system to perform.

• It can also be used to automate tasks by writing scripts.

• Common shells in Linux include Bash, Zsh, and Ksh.

• Examples of shell commands include ls (list files), cd (change directory), and mkdir

Different types of joins include inner join, outer join, left join, and right join.

• Inner join: Returns rows when there is a match in both tables

• Outer join: Returns all rows when there is a match in one of the tables

• Left join: Returns all rows from the left table and the matched rows from the right table

• Right join: Returns all rows from the right table and the matched rows from the left table

Tuning a SQL query involves optimizing its performance by adjusting various factors.

• Identify slow performing queries using tools like SQL Profiler or Execution Plan.

• Optimize query structure by using appropriate indexes and avoiding unnecessary joins.

• Consider rewriting the query to use more efficient techniques like subqueries or CTEs.

• Update statistics on tables involved in the query to ensure accurate query execution p...read more

Errors in log files in Linux can be found by searching for keywords, timestamps, and error codes.

• Use 'grep' command to search for specific keywords or error codes in log files

• Look for timestamps to identify when errors occurred

• Check for any error messages or warnings that may indicate issues

• Use 'tail' command to view the end of log files for recent errors

• Consider using 'journalctl' command for system logs in systemd-ba

Use dynamic programming to find the longest palindromic substring in a given string.

• Iterate through the string and expand around each character to find palindromes.

• Store the length of the longest palindrome found so far.

• Return the substring based on the start and end indices of the longest palindrome.

To serialize and deserialize a tree, use a recursive approach to traverse the tree and store the data in a suitable format.

• Use pre-order traversal to serialize the tree by storing the node values in a list or string.

• For deserialization, reconstruct the tree by recursively building nodes from the serialized data.

• Consider using JSON or XML format for serialization to easily store and retrieve tree structure.

Use regex library to match given regex with string.

• Use a regex library like re in Python to match the given regex with the string.

• Check if the regex matches the string using the library functions.

• Handle cases where the regex contains special characters like . and * appropriately.

Throttling is a technique used to control the rate of requests sent to a server.

• Throttling helps prevent server overload by limiting the number of requests processed at a time.

• Implementing a throttle function involves setting a maximum request rate and delaying excess requests.

• Example: Implementing a throttle function in a web application to limit the number of API calls made to a third-party service.

• Example: Throttlin...read more

Sort the squares of elements in a sorted array and return the sorted response.

• Iterate through the array and square each element.

• Store the squared values in a new array.

• Sort the new array and return it.

A promise is a commitment to do something in the future, typically used for asynchronous operations in JavaScript.

• Promises are used to handle asynchronous operations in JavaScript.

• They represent a value that may be available now, in the future, or never.

• Promises have three states: pending, fulfilled, or rejected.

• Example: new Promise((resolve, reject) => { setTimeout(() => resolve('Done!'), 1000); });

Event loop is a mechanism that allows for asynchronous execution of code by managing the order of events in a single thread.

• Event loop continuously checks the call stack for any functions that need to be executed, and processes them in a non-blocking manner.

• Different types of queues in event loop include microtask queue (Promise callbacks), macrotask queue (setTimeout, setInterval callbacks), and animation frame queue

Virtual DOM is a lightweight copy of the actual DOM, used to improve performance by minimizing direct manipulation of the real DOM.

• Virtual DOM is a concept used in frameworks like React to optimize rendering performance.

• Changes are first made to the virtual DOM, which is then compared to the real DOM to identify the minimal updates needed.

• This approach reduces the number of actual DOM manipulations, resulting in faster...read more

Scope refers to the visibility and accessibility of variables in a program. Logical operators are used to perform logical operations in code.

• Scope in programming refers to where in the code a variable can be accessed. It can be global, local, or block scope.

• To solve an error in the code, first identify the error message or behavior causing the issue. Then, debug the code by checking for syntax errors, logical errors, o...read more

To get data in a table using js, you can use DOM manipulation methods like getElementById or querySelector. Other ways to print output include console.log and innerHTML. A block in js is a set of statements enclosed in curly braces.

• Use getElementById or querySelector to get data in a table using js

• Other ways to print output include console.log and innerHTML

• A block in js is a set of statements enclosed in curly braces,

Seeking new challenges and growth opportunities in a different environment.

• Looking for new challenges and opportunities for growth

• Interested in gaining experience in a different industry or technology

• Seeking a better work-life balance or company culture

• Wanting to work with a different team or leadership style