100+ Application Support Engineer Interview Questions and Answers

SQL is a database language used to manage data. Unix is an operating system used for servers and workstations.

• SQL is used to create, modify, and query databases.

• Unix is a command-line interface used for file management, process control, and networking.

• SQL can be used with various database management systems like MySQL, Oracle, and SQL Server.

• Unix commands include ls, cd, grep, and chmod.

• SQL and Unix are commonly used in web development and data analysis.

To add a column without using create, you can use the ALTER TABLE statement.

• Use the ALTER TABLE statement to add a new column to an existing table

• Specify the table name and the new column name, data type, and any other constraints

• Example: ALTER TABLE table_name ADD column_name data_type;

To check how much space is left in the current drive, you can use the 'df' command in the terminal.

• Use the 'df' command followed by the '-h' flag to display the disk space in a human-readable format.

• Look for the 'Available' column to see how much space is left on the current drive.

• Example: 'df -h' will show you the disk space usage on all mounted filesystems.

Answers to Linux-related questions for Application Support Engineer role

• Heap dump files can be found using the jmap command

• The superuser has complete control over the system and can perform any action

• chmod command can be used to modify file permissions

• Commands like df, du, and ls can be used to check disk usage

• GREP command is used to search for a specific pattern in a file or output

I will investigate the root cause of the slow performance and take appropriate actions.

• Check server resources usage

• Analyze application logs

• Identify bottleneck areas

• Optimize database queries

• Implement caching mechanisms

• Upgrade hardware or software if necessary

Use SQL JOIN operations to fetch matching rows from two tables based on a common key.

• Use INNER JOIN to fetch rows that have matching values in both tables. Example: SELECT * FROM table1 INNER JOIN table2 ON table1.id = table2.id;

• Use LEFT JOIN to fetch all rows from the first table and matching rows from the second. Example: SELECT * FROM table1 LEFT JOIN table2 ON table1.id = table2.id;

• Use RIGHT JOIN to fetch all rows from the second table and matching rows from the first. Ex...read more

File with 644 permissions in Linux means read and write access for owner, and read-only access for group and others.

• Owner can read and write the file

• Group and others can only read the file

• Permissions are represented as three sets of three bits (rwx)

A pipe in operating systems is a form of inter-process communication that allows the output of one process to be used as the input of another process.

• A pipe is a method for passing data between processes in a unidirectional manner.

• It is typically used when the output of one process needs to be input into another process.

• Pipes are created using the pipe() system call in Unix-like operating systems.

• An example of using a pipe is when using the 'ls | grep' command in a Unix shell...read more

SQL queries for finding odd/even rows, duplicates, and deleting duplicates. Also covers constraints, joins, and DDL/DML differences.

• To find odd/even rows, use the MOD function with a value of 2

• To find duplicate rows, use the GROUP BY clause with the HAVING clause

• To delete duplicate rows, use the DELETE statement with a subquery

• Constraints ensure data integrity by enforcing rules on columns or tables

• Joins combine data from multiple tables based on a common column

• DDL (Data Defi...read more

Commonly used Unix commands

• ls - list directory contents

• cd - change directory

• mkdir - make directory

• rm - remove files or directories

• cp - copy files or directories

• mv - move or rename files or directories

• grep - search for patterns in files

• cat - concatenate and display files

• chmod - change file permissions

• ssh - secure shell remote login

Fetch project details where the project name starts with 'A' using SQL query.

• Use SQL SELECT statement to retrieve data from the 'project' table.

• Utilize the WHERE clause with the LIKE operator to filter results.

• Example SQL query: SELECT * FROM project WHERE project_name LIKE 'A%';

• The '%' wildcard allows for any characters to follow 'A'.

• Ensure proper indexing on the project_name column for performance.

To take a backup of a table in MySQL, you can use the mysqldump command.

• Use the mysqldump command followed by the database name and table name to backup a specific table.

• Specify the username and password for the MySQL database when using mysqldump.

• You can also backup multiple tables or the entire database using mysqldump.

• Save the backup file in a secure location for future restoration if needed.

Crontab commands are used in Linux for scheduling tasks at specific times.

• crontab -e: Edit the crontab file

• crontab -l: List the current crontab entries

• crontab -r: Remove the current crontab file

• crontab -u username: Specify the username whose crontab is to be modified

• */5 * * * * command: Run 'command' every 5 minutes

Basic components of Linux include kernel, shell, commands, utilities, and file system.

• Kernel - core component that manages hardware resources

• Shell - interface for users to interact with the system

• Commands - instructions given to the system for specific tasks

• Utilities - additional tools for system management

• File system - structure for organizing and storing data

Application Support Engineers are responsible for troubleshooting and resolving technical issues related to software applications.

• Provide technical support to end-users and clients

• Identify and resolve software bugs and errors

• Collaborate with development teams to enhance application functionality

• Document and maintain knowledge base articles for troubleshooting

• Monitor application performance and identify areas for improvement

Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. Denormalization is the opposite process.

• Normalization involves breaking down data into smaller, more manageable tables to reduce redundancy and dependency.

• Denormalization involves combining tables to improve query performance by reducing the number of joins needed.

• Normalization helps maintain data integrity by reducing the risk of anomalies such as update, insert, an...read more

LVM stands for Logical Volume Manager, used to manage disk space efficiently by allowing for dynamic resizing of volumes.

• LVM allows for easy resizing of volumes without needing to unmount the filesystem

• It provides features like striping, mirroring, and snapshots for data management

• LVM is required for efficient storage management in enterprise environments

The '/proc' file system in Linux is a virtual file system that provides detailed information about the system's hardware, processes, and kernel.

• It is a virtual file system that exists only in memory and does not correspond to any physical disk storage.

• It provides real-time information about various system resources such as CPU, memory, processes, and devices.

• Users can access and manipulate system information by reading from and writing to files within the '/proc' directory.

• Fo...read more

Use grep command with -i flag to print lines containing 'july' ignoring case.

• Use the following command: grep -i 'july' file.txt

• Replace 'file.txt' with the actual file name if applicable

• The -i flag makes the search case-insensitive

Five essential UNIX commands are ls, cd, pwd, mkdir, and rm.

• ls - list directory contents

• cd - change directory

• pwd - print working directory

• mkdir - make directory

• rm - remove files or directories

Common SQL commands for data manipulation and retrieval

• SELECT - retrieve data from a table

• INSERT - insert data into a table

• UPDATE - update existing data in a table

• DELETE - delete data from a table

• CREATE - create a new table or database

• ALTER - modify the structure of a table

• DROP - delete a table or database

• JOIN - combine data from multiple tables

• GROUP BY - group data based on a specific column

• ORDER BY - sort data based on a specific column

Interview questions for Application Support Engineer focus on technical skills, problem-solving, and customer service abilities.

• Technical questions may include troubleshooting scenarios, e.g., 'How would you resolve a database connectivity issue?'

• Behavioral questions assess teamwork and communication, e.g., 'Describe a time you handled a difficult customer.'

• Situational questions test problem-solving skills, e.g., 'What steps would you take if an application goes down unexpect...read more

Use secure file transfer protocols like SFTP or SCP to move files between servers.

• Use SFTP (SSH File Transfer Protocol) or SCP (Secure Copy Protocol) for secure file transfer.

• Ensure servers have proper firewall rules and access controls in place.

• Encrypt files before transferring them to ensure data security.

• Regularly update software and patches to prevent vulnerabilities.

• Consider using VPN for added security during file transfer.

SQL delete syntax and commands.

• Use the DELETE statement followed by the table name.

• Add a WHERE clause to specify the rows to be deleted.

• Use the TRUNCATE statement to delete all rows in a table.

• Use the DROP statement to delete an entire table.

• Be careful when deleting data as it cannot be recovered.

• Examples: DELETE FROM table_name WHERE column_name = value;

• TRUNCATE TABLE table_name;

• DROP TABLE table_name;

Clustered index determines the physical order of data in a table while non-clustered index creates a separate structure.

• Clustered index sorts and stores the data rows in the table based on their key values

• Non-clustered index creates a separate structure that contains the key values and a pointer to the data row

• A table can have only one clustered index while multiple non-clustered indexes can be created

• Clustered index is faster for retrieving large amounts of data while non-cl...read more

Indices are values that point to specific data within a data structure. They are used to access and manipulate data efficiently.

• Indices are commonly used in arrays to access specific elements.

• They can also be used in databases to improve search performance.

• Indices can be created on columns in a table to speed up queries.

• In programming, indices are often used in loops to iterate over data structures.

• Indices can also be used in mathematical operations, such as calculating the a...read more

A table with 3-4 columns is created to store and organize data in a structured manner.

• Columns represent different attributes or properties of the data.

• Each row in the table represents a unique record or entry.

• Columns can have different data types such as text, numbers, dates, etc.

• Primary key column can be used to uniquely identify each record.

• Foreign key columns can establish relationships between tables.

• Example: A table for customer data may have columns like 'ID', 'Name', '...read more