Top 30 SQL Server DBA Interview Questions and Answers

SQL Server DBA interview questions are crucial for evaluating your expertise in managing and maintaining SQL Server databases. Whether you're an experienced Database Administrator or preparing for your first DBA interview, understanding the types of questions commonly asked can give you an edge.

SQL Server Database Administrators, also called Server DBAs, are responsible for the design, maintenance, security, memory, and support of SQL Server Databases. The job growth projection for the next decade is 9%. To lay hands on this highly promising job you need to have the correct knowledge and skill set, and foremost you must have a knack for clearing the interview questions.

SQL Server DBA interview questions are asked in both fresher and experienced programmers' SQL interviews. If you're getting ready for an upcoming SQL interview, going over these SQL Server DBA interview questions and answers can help you ace it.

In this article, we’ll look at some common basic and advanced SQL Server DBA interview questions with answers, as well as some sample interview questions asked at SQL technical interviews.

Most Popular SQL Server DBA Interview Questions With Answers

These interview questions and answers for SQL Server DBAs are commonly asked of both freshers and experienced developers. Practising these questions will prepare you for your tech interview.

Q1. What do you mean by Extent in an SQL Server Database?

In answering this SQL server DBA interview question, you can say that an extent is a basic unit of measuring space for indexes and tables in the database. Typically, it consists of 8 contiguous pages. Each of these pages are upto 8 KB in size, meaning an extent's size is 64 KB. 

It serves two purpose:

• Uniform extent: All the 8 pages in the extent are from a single object like a table or an index.
• Mixed extent: Here, each of the 8 pages of an extent can be allocated to different objects.

It is to be noted that when a table or an index is small, the SQL server tends to use mixed extents to save space. However, as the object expands, it starts using the uniform extent to extract maximum performance and efficient management.

Q2. What are the contents of the page header in an SQL server database?

You can answer thsi SQL DBA interview question by stating that each data page consists of a page header that stores all the essential metadata about the page. The size of the page header is always going to be 96 bytes and will appear at the beginning of each page. With the infomration provided by the page header, the SQL server can be managed and data can be avigated efficiently. 

The contents of the page header are - Index of Data and Free Space.

Q3. What are the different types of System databases?

In answering this SQL server DBA interview question, you can say that the following six are the different types of system databases:

• Resource
• TempDB
• Distribution
• Model
• Master
• MSDB

Q4. What is the Syntax used to create an SQL database?

The syntax used to create an SQL database is - Create database <databasename>. The following is the basic syntax used to create an SQL database:

CREATE DATABASE database_name;

In addition, you can also specify additional functions like file locations, size, etc. for data & log files. 

The following is an example of a database named SalesDB that has specific configuations for its data and log files:

CREATE DATABASE SalesDB

ON

(             
         NAME = SalesData,          
         FILENAME = 'C:\SQLData\SalesData.mdf',
         SIZE = 10MB,
         MAXSIZE = 100MB,
         FILEGROWTH = 5MB

)
LOG ON
(
         NAME = SalesLog,
         FILENAME = 'C:\SQLData\SalesData.ldf',
         SIZE = 5MB,
         MAXSIZE = 50MB,
         FILEGROWTH = 5MB
);

Here, SalesData.mdf is the main data file, SalesLog.ldf is the log file, and the database starts with a size of 10MB for data and 5MB for log. It has the space for future growth as needed. 

Q5. How do you create databases with specific file locations in SQL?

This is one of the most common SQL server DBA interview questions asked in technical interviews. To create a database with a specific file location, the following command is used:

Restore Database <database name> from disk='<Backup file location + file name>’

Q6. What are some third-party tools used to create and support SQL Server databases?

Some third-party tools that are commonly used to create and support SQL server databases include:

• SQL Doc2 - Used to document SQL databases
• SQL Check - USed to monitor memory and server activities
• SQL Backup5 - This is used to backup SQL databases
• Litespeed 5.0 - Used mainly to restore and backup databases
• SQL Prompt - used to provide IntelliSense for SQL databases

Q7. What is SSMS?

The SQL Server Management Studio (SSMS), is a popular software application used for designing, creating, configuring, and managing components inside the Microsoft SQL database. It is one of the widely used applications for Microsoft SQL databases.

Q8. What are the Methods used to backup SQL databases?

You can answer this SQL server database administrator interview question by stating that there are several methods that help backup the SQL databases, ensuring the safety and recoverability of the data in case of any failure. 

These methods can be used either individually or in a combination, depending on the backup strategy you use and the business requirements.

The methods used to backup SQL databases are - SQL Server Management Studio (SSMS) and Transact-SQL (T-SQL).

Q9. What do you understand about Hotfixes in the content of SQL Server Databases?

Hotfixes are software packages that contain multiple files specifically deployed to fix problems in an SQL database. Hotfixes are commonly developed and used by developers to rectify SQL database problems that may arise from time to time. The following are some key characterstics of hotfixes:

• Issue-specific: Hotfixes fix a specific problem or a set of closely related issues that may be the cause of errors, data corruption, or performance degradation in the SQL server.
• Limited testing: The hotfixes are designed for quick resolution. Therefore, their testing is less extensive as compared to service packs or cumulative updates.
• Minimal changes: There are only minimal changes in the hotfixes related to the existing codebase and configuration. As a result, they minimize the impact on the overall system.
  

Q10. What are some benefits of employing SQL third-party tools to maintain and support SQL Server databases?

This is a common SQL Server DBA interview question asked at technical interviews. Some benefits of using third-party tools include:

• Backups are secured through encryption
• Security of databases is maintained
• Memory is allocated uniformly and consistently
• Faster recovery options
• Individual database objects can be easily recovered
• Backup histories and schedules can be viewed seamlessly

Sample SQL Server DBA Interview Questions for Practice

Here are some additional sample SQL database administrator interview questions that you can practice before your tech interview. These basic and advanced questions will help you prepare your answers in advance and make it easier to crack the technical round.

1. What do you understand by Clustering in SQL Server Databases?
2. What do you understand by Mirroring?
3. What is log shipping?
4. What do you understand by Replication?
5. What are some methods used to Start and Stop services?
6. How do you optimally monitor SQL servers? Would you use third-party tools?
7. List the different types of backups used in SQL server databases?
8. What is the Syntax to insert data into tables in an SQL database?
9. What command would you use to see execution plans by users?
10. How would you go about deleting current-day entries in a table that has a timestamp column?
11. What is SSIS, and what are its uses?
12. What Syntax would you use to get the top 60 records from a given SQL table?
13. What are the different backup types used in SQL server databases?
14. What is the action plan to be followed if an SQL server isn’t responding?
15. What do you understand about T-SQL?
16. How would you decide between passive and active nodes in an SQL server database?
17. How do you go about SQL server monitoring?
18. How do you ensure to maintain the security of an SQL server database?
19. How do you allocate memory to components in an SQL server database?
20. What is the process to upgrade SQL server versions?

The above SQL server DBA interview questions will help you prepare thoroughly for your upcoming SQL or software engineering interview.

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FAQs: SQL Server DBA Interview Questions

Q1. What type of SQL Server DBA interview questions can you expect at technical interviews?

SQL Server DBA interview questions at technical interviews are typically around different System Databases, core SQL database concepts such as clustering, mirroring, replication, server, and database security, allocating memory, and retrieving data from the database servers.

Q2. What is the typical role of an SQL Database Administrator?

SQL Database Administrators are typically involved with designing and managing the SQL server, allocating memory, organizing data, enabling user interaction with the server, and ensuring that data contained in the server is secure.

Q3. How many years of experience do you need as an SQL DBA to apply to FAANG+ companies?

Most top companies, including FAANG+ companies, prefer administrators with proven database and server-side experience. These companies require candidates to have 3-4 of experience designing and managing SQL databases.

Q4. Which are the four main types of Database Console Commands?

This is a standard SQL Server DBA interview question asked at technical interviews. The four main types of DBCCs are Information Commands, Validation Commands, Maintenance Commands, and Miscellaneous Commands.

Q5. What are the types of recovery models available in SQL server databases?

The three types of available recovery models include - Simple Recovery, Sull Recovery, and Bulked Log Recovery.

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