Showing posts with label database. Show all posts
Showing posts with label database. Show all posts

May 08, 2022

Top 20 Oracle 10g Interview Questions and Answers


             The Oracle Database 10g Standard Edition is designed for medium-sized businesses. Oracle's Real Application Cluster features are included to protect against hardware failures. It's simple to set up and configure, and it includes its own clustering software, storage management, and other self-managing features. Oracle Database 10g Standard Edition maintains all of your data and lets all of your business applications to benefit from Oracle Database's renowned performance, security, and reliability. It also has full upward compatibility with Oracle Database 10g Enterprise Edition, ensuring that your investment is protected as your needs change.

Oracle Fusion Applications interview Questions and Answers

Ques. 1): What are the components of an Oracle database's logical database structure?


The following are the components of Oracle's logical database structure:

Tablespaces: Tablespaces are the logical storage units that make up a database. This tablespace is a collection of logical structures that are linked together. To be more specific, tablespace groupings are linked to logical structures.

Database Schema Objects: A schema is a set of database objects that belong to a single user. Tables, indexes, views, stored procedures, and other objects are among the objects. The user is the account in Oracle, and the schema is the object. It is also possible to have a schema without specifying a user in database platforms.

Oracle Accounts Payables Interview Questions and Answers

Ques. 2): What is the connection between the database, tablespace, and data file?


An Oracle database has one or more tablespaces, which are logical storage units. Each tablespace in an Oracle database is made up of one or more datafiles. The complete data of databases is stored in these tablespaces. When we talk about datafiles, we're talking about the physical structure that tells the operating system which Oracle software is running.

Oracle ADF Interview Questions and Answers

Ques. 3): What is the difference between DB file sequential read and DB File Scattered Read ?


DB File Scattered Read is related to index read, whereas DB File Sequential Read is related to whole table scan. DB File sequential read reads blocks into contiguous memory, whereas DB File dispersed read reads multiple blocks into buffer cache.

Oracle Access Manager Interview Questions and Answers

Ques. 4): Which variables should be addressed when establishing a table index? How do I choose a column for indexing?


The size of the database and the amount of data determine how an index is created. If the table is vast and only a few data points are required for selection or reporting, an index must be created. Cardinality and frequent usage in the where condition of a select query are two primary reasons for selecting columns for indexing. Because configuring main key or unique key immediately creates unique index, the business rule also forces the creation of indexes like primary keys.

It is important to note that creation of so many indexes would affect the performance of DML on table because in single transaction should need to perform on various index segments and table simultaneously.

Oracle Fusion HCM Interview Questions and Answers

Ques. 5): What does Oracle's ANALYZE command do?


This command "Analyze" is used to conduct different operations on an index, table, or cluster. The following is a list of Oracle commands that use the ANALYZE command:

The Analyze command is used to find migrated and chained table or cluster rows.

It is used to verify an object's structure.

This assists in gathering statistics about the object that the user is using, which are subsequently put in the data dictionary.

It also aids in the deletion of statistics from the data dictionary that are used by an object.

Oracle SCM Interview Questions and Answers

Ques. 6): What is the DUAL table's data type?


The Dual table is a single-column table in the Oracle database. Dummy is a single Varchar2(1) column in this table with the value 'X'.

Oracle Financials Interview questions and Answers

Ques. 7): Is it possible to create an index online?


YES. Indexes can be created and rebuilt online. This allows you to change basic tables while also building or rebuilding indexes on those tables. DML actions are permitted while the index is being built, but DDL operations are not permitted.

When constructing or rebuilding an index online, parallel execution is not supported.

CREATE INDEX emp_name ON emp (mgr, emp1, emp2, emp3) ONLINE;

Oracle Cloud Interview Questions and Answers

Ques. 8): When the R/3 system is active, why is a small dump written during an offline backup?


BRBACKUP terminates the database during an offline backup, however the present R/3 system is unaware of this. As a result, the first work process that loses its database connection creates a small dump. Until the database is available again, all work processes move into reconnect mode. As a result, because the database cannot be accessed, one (or more) brief dumps are usually produced during an offline backup.

Oracle PL/SQL Interview Questions and Answers

Ques. 9): How can you track a user's password change in Oracle?


Oracle only keeps track of the password's expiration date based on when it was last modified. You may discover when a password was last changed by listing the view DBA USERS.EXPIRY DATE and subtracting PASSWORD LIFE TIME. The PTIME column in the USER$ database (on which the DBA USERS view is based) can also be used to check the last password change time. However, if PASSWORD REUSE TIME and/or PASSWORD REUSE MAX are configured in a profile given to a user account, you can look up the password change date in the dictionary table USER HISTORY$.

SELECT user$.NAME, user$.PASSWORD, user$.ptime, user_history$.password_date

FROM SYS.user_history$, SYS.user$

WHERE user_history$.user# = user$.user#;

Oracle SQL Interview Questions and Answers

Ques. 10): What is Secure External password Store (SEPS) ?


You can store password credentials for connecting to databases using SEPS by utilising a client-side Oracle wallet, which also stores signing credentials. This capability has been available since Oracle 10g. Thus, embedded username and passwords were no longer required in application code, scheduled jobs, or scripts. This decreases risk because passwords are no longer accessible, and password management policies can be implemented more quickly without having to alter application code whenever the login and password change.

Oracle RDMS Interview Questions and Answers

Ques. 11): Why do we require the CASCADE option when using the DROP USER command to drop a user, and why do "DROP USER" instructions fail when we don't use it?


If a user has an object, you will not be able to delete that user without using the CASCADE option. The DROP USER command with the CASCADE option deletes the user and all associated items. Because this is a DDL command, rollback is not possible after it has been executed.

BI Publisher Interview Questions and Answers

Ques. 12): What is the difference between Redo, Undo, and Rollback?


When it comes to Redo, Rollback, and Undo, I always get a little confused. They all sound pretty much the same, or at least very similar.

Every Oracle database has a collection of redo log files (two or more). The redo log keeps track of all data changes, including both uncommitted and committed ones. Oracle saves archive redo logs in addition to online redo logs. In recovery scenarios, all redo logs are used. Rollback: More specifically, section rollback. The data in rollback segments is saved as it was before any modifications were made. The redo log, on the other hand, is a record of the inserts, updates, and deletions.

Undo: Rollback segments. They both are really one in the same. Undo data is stored in the undo tablespace. Undo is helpful in building a read consistent view of data.


Ques. 13): Do you have more than three Linux instances running? How do you figure out which shared memory and semaphores belong to which instance?


Oracle provides an undocumented utility called Oradebug. The oradebug help command displays a list of oracle commands.

SQL>oradebug setmypid

SQL>oradebug ipc

SQL>oradebug tracfile_name


Ques. 14): Why aren't all Oracle faults recorded in the Alert Log?


In the Alert Log, Oracle only logs critical problems. The majority of Oracle error codes are not recorded (unfortunately this may also include error codes that are genuinely critical). As a result, it's common to discover faults in the Oracle application that aren't visible in the Alert Log.


Ques. 15): There is no room available to add datafiles to enhance temp tablespace because it is completely full. What can you do to free up TEMP tablespace in that case?


Closing some of the database's idle sessions will help you free up some TEMP space. You can also make use of:

Alter Tablespace PCTINCREASE 1' ;

'Alter Tablespace PCTINCREASE 0;


Ques. 16): What is the difference between row chaning and row migration?


Row Migration:  When an update to a row causes it to no longer fit on the block, it migrates (with all of the other data that exists there currently). A migration means that the entire row will be moved, with only the «forwarding address» remaining. As a result, the original block only has the new block's rowid and the entire row is transferred.

Row Chaining: A single database block cannot hold more than one row. For example, if your database uses a 4KB blocksize and you need to insert an 8KB row, Oracle will use three blocks and save the information in pieces. Row chaining can occur under the following circumstances: Tables with a rowsize greater than the blocksize. Chained rows are common in tables containing LONG and LONG RAW columns. Oracle breaks broad tables split into sections, therefore tables with more than 255 columns will have chained rows. Rather of having a forwarding address on one block and data on another, we now have data on two or more blocks.


Ques. 17): How can I erase a data file that I accidentally created?


In most circumstances, you can use RESIZE or RENAME to fix a data file that was generated with the improper size or in the wrong location. You have the following alternatives if you want to drop the data file again:

A produced data file can only be erased during a tablespace reorganization up to and including Oracle 9i. There are no other viable alternatives.

As of Oracle 10g, an empty data file can also be dropped with the following command:


If there are still extents in the data file, this command fails with ORA-03262. In this case, the affected segments must first be relocated so that the extents are released.


Ques. 18): What is the ideal file size for data files?


It is impossible to provide a straightforward solution to this topic. In most cases, the size of the data files has no bearing on database activity. However, keep the following considerations in mind:

Make sure the Oracle parameter DB FILES is set high enough. Otherwise, once this limit is reached, new data files cannot be produced.

The fewer the datafiles, the faster they can be restored individually during a backup.

BEGIN BACKUP processes in online backups are likely to take longer the smaller the data files are, and hence the more data files there are.

Data files that are too large aggravate performance problems that are caused by inode locking, since parallel processes may become serialized on the data file inode.

On occasion, size restrictions may prevent the system from using data files that exceed a certain size (often 2GB).


Ques. 19): Why does the order of the online redo logs occasionally change?


This redo log becomes the next redo log if the next online redo log is still archived and another redo log is available for overwriting. The order of the online redo logs is now altered. Because the alternative would be an archiver stuck, at least briefly, this behaviour is preferable.

Only if many archive processes run in parallel and do not run again when the redo logs are archived may this situation arise. To avoid this issue, see if the archiver's performance (I/O tuning) can be improved. You must also avoid getting an archiver stuck due to a fully operational archive file system.

This problem cannot occur if the number of archiver processes is limited to one by LOG_ARCHIVE_MAX_PROCESSES



Ques. 20): On my system, why do Oracle processes run as the sid>adm user?


By default, the UNIX PS command displays the true user, not the actual user. As a result, having adm as the displayed user for Oracle processes is not a problem. The only thing that matters is that the Oracle executable has the appropriate permissions.  



May 07, 2022

Top 20 AWS GuardDuty Questions and Answers

            Amazon GuardDuty is a threat detection service that monitors your AWS accounts and workloads for malicious behaviour in real time and provides detailed security findings for visibility and mitigation. Threat detection is provided by Amazon GuardDuty, which allows you to monitor and defend your AWS accounts, workloads, and data stored in Amazon Simple Storage Service on a continuous basis (Amazon S3). AWS CloudTrail Events, Amazon Virtual Private Cloud (VPC) Flow Logs, and domain name system (DNS) Logs are used by GuardDuty to analyse continuous metadata streams created from your account and network activity. GuardDuty also employs integrated threat intelligence to better identify threats, such as known malicious IP addresses, anomaly detection, and machine learning (ML).

AWS(Amazon Web Services) Interview Questions and Answers

Ques. 1): Is the predicted cost on the Amazon GuardDuty payer account for all linked accounts, or just for that specific payer account?


Only the cost of the individual payer account is included in the projected cost. The anticipated cost for the administrator account is the only thing you'll see.

AWS Cloud Interview Questions and Answers

Ques. 2): What do Amazon GuardDuty and Amazon Macie have in common?


Amazon GuardDuty helps identify risks like attacker reconnaissance, instance compromise, account compromise, and bucket compromise, and protects your AWS accounts, workloads, and data. Amazon Macie classifies what data you have, its security, and the access controls associated with it, allowing you to find and safeguard sensitive data in Amazon S3.

AWS RedShift Interview Questions and Answers

Ques. 3): How can I get Amazon GuardDuty to work?


With a few clicks in the AWS Management dashboard, Amazon GuardDuty may be set up and deployed. GuardDuty begins monitoring continuous streams of account and network activity in near real-time and at scale as soon as it is enabled. There is no need to install or administer any extra security software, sensors, or network equipment. Threat intelligence is pre-integrated into the service and is updated and maintained on a regular basis.

AWS Cloud Practitioner Essentials Questions and Answers

Ques. 4): How soon does GuardDuty begin to work?


When Amazon GuardDuty is on, it immediately begins scanning for malicious or illegal behaviour. The time it takes for you to start obtaining findings is determined by the level of activity in your account. GuardDuty only looks at activity that begins once it is enabled, not historical data. You'll get a finding in the GuardDuty console if GuardDuty detects any potential risks.

AWS EC2 Interview Questions and Answers

Ques. 5): Can I use Amazon GuardDuty to manage several accounts?


Yes, Amazon GuardDuty supports multiple accounts, allowing you to manage numerous AWS accounts from a single administrator account. All security findings are consolidated and sent to the administrator or Amazon GuardDuty administrator account for assessment and remediation when this feature is utilised. When utilising this configuration, Amazon CloudWatch Events are additionally aggregated to the Amazon GuardDuty administrator account.

AWS Lambda Interview Questions and Answers

Ques. 6): Do I have to enable AWS CloudTrail, VPC Flow Logs, and DNS logs for Amazon GuardDuty to work?


No. Amazon GuardDuty pulls independent data streams directly from AWS CloudTrail, VPC Flow Logs, and AWS DNS logs. You don’t have to manage Amazon S3 bucket policies or modify the way you collect and store logs. GuardDuty permissions are managed as service-linked roles that you can disable GuardDuty to revoke at any time. This makes it easy to enable the service without complex configuration, and eliminates the risk that an AWS Identity and Access Management (IAM) permission modification or S3 bucket policy change will affect service operation. It also makes GuardDuty extremely efficient at consuming high-volumes of data in near real-time without affecting the performance or availability of your account or workloads.

AWS Cloud Security Interview Questions and Answers

Ques. 7): Is Amazon GuardDuty a domestic or international service?


GuardDuty is a regional service provided by Amazon. The Amazon GuardDuty security findings remain in the same areas where the underlying data was generated, even when multiple accounts are enabled and several regions are used. This ensures that the data being evaluated is geographically specific and does not cross AWS regional boundaries. Customers can use Amazon CloudWatch Events to aggregate security discoveries produced by Amazon GuardDuty across regions, pushing results to a data repository under their control, such as Amazon S3, and then aggregating findings as needed.

AWS Simple Storage Service (S3) Interview Questions and Answers

Ques. 8): Is Amazon GuardDuty capable of automating preventative actions?


You can build up automated preventative measures based on a security finding with Amazon GuardDuty, Amazon CloudWatch Events, and AWS Lambda. For example, based on security discoveries, you can develop a Lambda function to adjust your AWS security group rules. If a GuardDuty report indicates that one of your Amazon EC2 instances is being probed by a known malicious IP, you may use a CloudWatch Events rule to automatically adjust your security group rules and limit access on that port.

AWS Fargate Interview Questions and Answers

Ques. 9): I'm a new Amazon GuardDuty user. Are my accounts protected by GuardDuty for S3 by default?


Yes. GuardDuty for S3 protection will be enabled by default for all new accounts that enable GuardDuty via the console or API. Unless "auto-enable for S3" is enabled, new GuardDuty accounts established using the AWS Organizations "auto-enable" functionality will not have GuardDuty for S3 protection set on by default.

AWS SageMaker Interview Questions and Answers

Ques. 10): What is Amazon GuardDuty for EKS Protection and how does it work?


Amazon GuardDuty for EKS Protection is a GuardDuty functionality that analyses Kubernetes audit logs to monitor Amazon Elastic Kubernetes Service (Amazon EKS) cluster control plane behaviour. GuardDuty is connected with Amazon EKS, allowing it direct access to Kubernetes audit logs without the need to enable or store them. These audit logs are chronological records that capture the sequence of actions performed on the Amazon EKS control plane and are security-relevant. GuardDuty can use these Kubernetes audit logs to conduct continuous monitoring of Amazon EKS API activity and apply proven threat intelligence and anomaly detection to discover malicious behaviour or configuration changes that could expose your Amazon EKS cluster to unauthorised access.

AWS DynamoDB Interview Questions and Answers

Ques. 11): Is GuardDuty for EKS Protection available for a free trial?


There is a 30-day free trial available. Each new Amazon GuardDuty account in each region gets a free 30-day trial of GuardDuty, which includes GuardDuty for EKS Protection. Existing GuardDuty accounts are eligible for a free 30-day trial of GuardDuty for EKS Protection. The post-trial expenditures estimate can be seen on the GuardDuty console use page during the trial period. You will be able to see the expected fees for your member accounts if you are a GuardDuty administrator. The AWS Billing dashboard will show you the true expenses of this functionality after 30 days.

AWS Cloudwatch interview Questions and Answers

Ques. 12): What are Amazon GuardDuty's main advantages?


Amazon GuardDuty makes it simple to keep track of your AWS accounts, workloads, and Amazon S3 data in real time. GuardDuty is fully independent of your resources, so your workloads will not be impacted in terms of performance or availability. Threat intelligence, anomaly detection, and machine learning are all integrated into the service. Amazon GuardDuty generates actionable warnings that are simple to connect with current event management and workflow systems. There are no upfront expenses, and you only pay for the events that are examined; there is no need to install additional software or pay for threat intelligence stream subscriptions.

AWS Elastic Block Store (EBS) Interview Questions and Answers

Ques. 13): Is there a free trial available?


Yes, any new Amazon GuardDuty account can try the service for free for 30 days. During the free trial, you get access to the full feature set and detections. The amount of data handled and the expected daily average service charges for your account will be displayed by GuardDuty. This allows you to try Amazon GuardDuty for free and estimate service costs beyond the free trial period.

AWS Amplify Interview Questions and Answers

Ques. 14): Does Amazon GuardDuty assist with some of the PCI DSS (Payment Card Industry Data Security Standard) requirements?


GuardDuty examines events from a variety of AWS data sources, including AWS CloudTrail, Amazon VPC Flow Logs, and DNS logs. Threat intelligence feeds from AWS and other providers, such as CrowdStrike, are also used to detect unusual activities. Foregenix produced a white paper evaluating Amazon GuardDuty's effectiveness in meeting compliance standards, such as PCI DSS requirement 11.4, which mandates intrusion detection solutions at crucial network points.

AWS Django Interview Questions and Answers

Ques. 15): What types of data does Amazon GuardDuty look at?


AWS CloudTrail, VPC Flow Logs, and AWS DNS logs are analysed by Amazon GuardDuty. The service is designed to consume massive amounts of data in order to process security alerts in near real time. GuardDuty gives you access to built-in cloud detection algorithms that are maintained and continuously upgraded by AWS Security.

AWS Glue Interview Questions and Answers

Ques. 16): Is Amazon GuardDuty in charge of my logs?


No, your logs are not managed or stored by Amazon GuardDuty. GuardDuty analyses and discards any data it consumes in near real time. GuardDuty is able to be highly efficient, cost-effective, and lower the danger of data remanence as a result of this. You should use AWS logging and monitoring services directly for log delivery and retention, as they provide full-featured delivery and retention options.

AWS VPC Interview Questions and Answers

Ques. 17): What is Amazon GuardDuty threat intelligence?


Amazon GuardDuty threat intelligence consists of known attacker IP addresses and domain names. GuardDuty threat intelligence is provided by AWS Security as well as third-party providers like Proofpoint and CrowdStrike. These threat intelligence streams are pre-integrated and updated on a regular basis in GuardDuty at no additional charge.

AWS Aurora Interview Questions and Answers

Ques. 18): Is there any impact on my account's performance or availability if I enable Amazon GuardDuty?


No, Amazon GuardDuty is fully separate from your AWS resources, and there is no chance of your accounts or workloads being affected. GuardDuty can now work across several accounts in an organisation without disrupting existing processes.

AWS DevOps Cloud Interview Questions and Answers

Ques. 19): What is Amazon GuardDuty capable of detecting?


Built-in detection techniques created and optimised for the cloud are available with Amazon GuardDuty. AWS Security is in charge of maintaining and improving the detection algorithms. The following are the key detection categories:

Peculiar API activity, intra-VPC port scanning, unusual patterns of failed login requests, or unblocked port probing from a known rogue IP are all examples of reconnaissance by an attacker.

Cryptocurrency mining, malware using domain generation algorithms (DGAs), outbound denial of service activity, unusually high network traffic, unusual network protocols, outbound instance communication with a known malicious IP, temporary Amazon EC2 credentials used by an external IP address, and data exfiltration using DNS are all signs of an instance compromise.

AWS CloudFormation Interview Questions ans Answers

Ques. 20): How do security discoveries get communicated?


When a threat is detected, Amazon GuardDuty notifies the GuardDuty console and Amazon CloudWatch Events with a thorough security finding. As a result, alerts are actionable and simple to integrate into existing event management or workflow systems. The category, resource affected, and metadata linked with the resource, such as a severity rating, are all included in the findings.

AWS GuardDuty Questions and Answers

Top 20 Apache Flume Interview Questions and Answers

                    Flume is a standard, simple, robust, versatile, and extendable tool for ingesting data into Hadoop from a variety of data providers (webservers).
Apache Flume is a dependable and distributed log data collection, aggregation, and distribution system. It's a highly available, dependable service with adjustable recovery methods.
The Flume's main goal is to capture streaming data from various web servers and store it in HDFS. Its architecture is basic and adaptable, based on streaming data flows. It is fault-tolerant and provides a fault tolerance and failure recovery mechanism.

Apache Kafka Interview Questions and Answers
Ques. 1): What does Apache Flume stand for?
Apache Flume is an open source platform for collecting, aggregating, and transferring huge amounts of data from one or more sources to a centralised data source effectively and reliably. Flume's data sources can be customised, so it can injest any type of data, such as log data, event data, network data, social media produced data, email messages, message queues, and so on.

Apache Struts 2 Interview Questions and Answers

Ques. 2): Why Flume?
Apart from collecting logs from distributed systems, it is also capable of performing other use cases. like
It Collects readings from array of sensors
Also, it collects impressions from custom apps for an ad network
Moreover, it collects it readings from network devices in order to monitor their performance.
Also, preserves the reliability, scalability, manageability, and extensibility while it serves maximum number of clients with higher QoS.
Apache Spark Interview Questions and Answers 

Ques. 3): What role does Flume play in big data?
Flume is a dependable distributed service for aggregating and collecting massive amounts of streaming data into HDFS. Most big data analysts utilise Apache Flume to deliver data into Hadoop, Strom, Solr, Kafka, and Spark from various sources such as Twitter, Facebook, and LinkedIn.

Ques. 4): What similarities and differences do Apache Flume and Apache Kafka have?
When it comes to Flume, it uses Sinks to send messages to their destinations. However, with Kafka, you must use a Kafka Consumer API to accept messages from the Kafka Broker.

Apache Tomcat Interview Questions and Answers
Ques. 5): What is flume agent, exactly?
A Flume agent is a Java virtual machine (JVM) process that hosts the components that allow events to flow from an external source to the central repository or to the next destination.
For each flume data flow, the Flume agent connects the external sources, Flume sources, Flume Channels, Flume sinks, and external destinations. Flume agent accomplishes this by mapping sources, channels, sinks, and other components, as well as defining characteristics for each component, in a configuration file.

Apache Drill Interview Questions and Answers
Ques. 6): How do you deal with agent errors?
If a Flume agent fails, all flows hosted on that agent are terminated.
Flow will resume once the agent is restarted. All events stored in the chavvels when the agent went down are lost if the channel is set up as an in-memory channel. Channels configured as file or other stable channels, on the other hand, will continue to handle events where they left off.

Apache Ambari interview Questions and Answers
Ques. 7): In Flume, how is recoverability ensured?
Flume organises events and data into channels. Flume sources populate Flume channels with events. Flume sinks consume channel events and publish them to terminal data storage. Failure recovery is handled by channels. Flume supports a variety of channels. In-memory channels save events in an in-memory queue for speedier processing. The local file system backs up file channels, making them durable.

Apache Tapestry Interview Questions and Answers
Ques. 8): What are the Flume's Basic Characteristics?
A Hadoop data gathering service: We can quickly pull data from numerous servers into Hadoop using Flume. For distributed systems, use the following formula: Flume is also used to import massive amounts of event data from social networking sites such as Facebook and Twitter, as well as e-commerce sites such as Amazon and Flipkart. Source code: It is an open-source programme. It can be activated without the use of a licence key. Flume may be resized vertically and horizontally.
1. A flume transports data from sources to sinks. This data collection might be planned or event-driven. Flume features its own query processing engine, which makes it simple to alter each fresh batch of data before sending it to its destination.
2. Apache Flume is horizontally scalable.
3. Apache Flume provides support for large sets of sources, channels, and sinks.
4. With Flume, we can collect data from different web servers in real-time as well as in batch mode.
5. Flume provides the feature of contextual routing.
6. If the read rate exceeds the write rate, Flume provides a steady flow of data between read and write operations.

Apache Ant Interview Questions and Answers
Ques. 9): What exactly is the Flume event?
Flume event is a data unit containing a set of string properties. The source receives events from an external source, such as a web server. Flume contains built-in capabilities to recognise the source format. Avro, for example, delivers events to the Flume from Avro sources.
Each log file is treated as an individual event. Each event has header and value sectors, which contain header information as well as the proper value for each header.

Apache Camel Interview Questions and Answers
Ques. 10): In Flume, explain the replication and multiplexing selections.
Answer: Channel selectors are used to handle many channels. Furthermore, based on the Flume header value, an event can be written to a single channel or numerous channels. If no channel selector is supplied for the source, it defaults to the Replicating selector.

Apache Cassandra Interview Questions and Answers
Ques. 11): What exactly is FlumeNG?
FlumeNG is nothing more than a real-time loader for streaming data into Hadoop. It basically uses HDFS and HBase to store data. As a result, if we wish to start with FlumeNG, we should know that it improves on the original flume.
Using the replicating selection, the same event is written to all of the channels in the source's channels list. We use the Multiplexing channel selection when the application has to broadcast distinct events to multiple channels.

Apache NiFi Interview Questions and Answers
Ques. 12): Could you please clarify what configuration files are?
The configuration of the agent is saved in a local configuration file. It contains information about each agent's source, sink, and channel. Name, type, and set of properties are all properties of each fundamental component, such as source, sink, and channel. To accept data from an external client, an Avro source, for example, requires the hostname and port number. In terms of capacity, the memory channel should have a maximum queue size. Sink should have File System URI, Path to Create Files, File Rotation Frequency, and other settings.

Apache Storm Interview Questions and Answers
Ques. 13): What is topology design in Apache Flume?
The initial step in Apache Flume is to verify all data sources and sinks, after which we may determine whether we need event aggregation or rerouting. When gathering data from multiple sources, aggregation and rerouting are required to redirect those events to a different place.

Ques. 14): Explain about the core components of Flume.
The core components of Flume are –
Event- The single log entry or unit of data that is transported.
Source- This is the component through which data enters Flume workflows.
Sink-It is responsible for transporting data to the desired destination.
Channel- it is the duct between the Sink and Source.
Agent- Any JVM that runs Flume.
Client- The component that transmits event to the source that operates with the agent.

Ques. 15): What is the data flow in Flume?
To transport log data into HDFS, we use the Flume framework. The log servers, on the other hand, generate events and log data. Flume agents are also running on these servers. Furthermore, the data generators provide the data to these agents.
To be more explicit, there is an intermediate node in Flume that collects data from these agents; these nodes are referred to as Collectors. There can be several collectors in Flume, just like there can be multiple agents.
After that, data from all of these collectors will be gathered and transferred to a central location. For example, HBase or HDFS. Refer to the Flume Data Flow diagram below for a better understanding of the Flume Data Flow paradigm.

Ques. 16): How can Flume be used with HBase?
Apache Flume can be used with HBase using one of the two HBase sinks –
HBaseSink (org.apache.flume.sink.hbase.HBaseSink) supports secure HBase clusters and also the novel HBase IPC that was introduced in the version HBase 0.96.
AsyncHBaseSink (org.apache.flume.sink.hbase.AsyncHBaseSink) has better performance than HBase sink as it can easily make non-blocking calls to HBase.
Working of the HBaseSink –
In HBaseSink, a Flume Event is converted into HBase Increments or Puts. Serializer implements the HBaseEventSerializer which is then instantiated when the sink starts. For every event, sink calls the initialize method in the serializer which then translates the Flume Event into HBase increments and puts to be sent to HBase cluster.
Working of the AsyncHBaseSink-
AsyncHBaseSink implements the AsyncHBaseEventSerializer. The initialize method is called only once by the sink when it starts. Sink invokes the setEvent method and then makes calls to the getIncrements and getActions methods just similar to HBase sink. When the sink stops, the cleanUp method is called by the serializer.

Ques. 17): What method is used to stream data from the hard drive?
Ans: The data is "streamed" off the hard disc by keeping the drive's maximum I/O rate for these huge blocks of data constant. The write-once, read-many-times pattern is the most efficient data processing pattern, according to HDFS.

Ques. 18): What distinguishes HBaseSink from AsyncHBaseSink?
To deliver the event to the Hbase system, Apache Flume HBaseSink and AsyncHBaseSink are both employed. The HTable API is used to transfer data to HBase in the case of HBaseSink, while the asynchbase API is used to send stream data to HBase in the case of AsyncHBaseSink. The callbacks are responsible for handling any failures.

Ques. 19): In Hadoop HDFS, what is Flume? How can you tell if your sequence data has been imported into HDFS?
It's another Apache Software Foundation top-level project designed to provide continuous data injection in Hadoop HDFS. The data can be any type of data, however Flume is best suited for handling log data, such as web server log data.

Ques. 20): What is the difference between streaming and HDFS?
Ans: Streaming simply means that you can get a continuous bitrate over a specific threshold when sending data, rather than having it come in bursts or waves. If HDFS is set up for streaming, it will very certainly enable seek, albeit with the added overhead of caching data for a steady stream.

May 06, 2022

Top 20 AWS CloudFormation Interview Questions and Answers


                        AWS CloudFormation is a configuration orchestration tool that lets you define your infrastructure in order to automate deployments. CloudFormation uses a declarative approach to configuration, which means you tell it how you want your environment to look and it follows your instructions.

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AWS CloudFormation is a service that assists you in modelling and setting up your Amazon Web Services resources so you can spend less time managing them and more time working on your AWS-based applications. You construct a template that outlines all of the AWS resources you want (such as Amazon EC2 instances or Amazon RDS DB instances), and AWS CloudFormation handles provisioning and configuration for you.

In addition to JSON, YAML may be used to generate CloudFormation templates. You may also use AWS CloudFormation Designer to graphically construct your templates and see how your resources are interconnected. 

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Ques. 1): Explain the working model of CloudFormation.


First, we must code our infrastructure in a template, which is a YAML or JSON text-based file.

Then we use the AWS CloudFormation tool to write our code locally. Otherwise, we can use the S3 bucket to store a YAML or JSON file.

Create a stack based on our template code using the AWS CF GUI or the Command Line Interface.

Finally, CloudFormation deploys resources, provisioned them, and configured the template we specified.

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Ques. 2): Are there any restrictions on how many resources may be produced in a stack?


See Resources in AWS CloudFormation quotas for more information on the number of resources you can define in a template. Smaller templates and stacks, as well as modularizing your application across multiple stacks, are best practises for reducing the blast radius of resource changes and troubleshooting issues with multiple resource dependencies faster, as smaller groups of resources have less complex dependencies than larger groups.

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Ques. 3): Describe the features of AWS CloudFormation.


By treating infrastructure as code, AWS CloudFormation makes it simple to model a collection of connected AWS and third-party resources, provision them rapidly and consistently, and manage them throughout their lifecycles.

  • Extensibility - Using the AWS CloudFormation CLI, an open-source tool that speeds the development process and includes local testing and code generation capabilities, you can create your own resource providers.
  • Management of multiple accounts and regions - CloudFormation With a single CloudFormation template, you can provision a common set of AWS resources across many accounts and regions. StackSets takes care of provisioning, updating, and deleting stacks automatically and safely, no matter where they are.
  • Authoring with JSON/YAML - CloudFormation allows you to model your whole cloud environment in text files using JSON/YAML. To define what AWS resources you wish to build and configure, you can use open-source declarative languages like JSON or YAML.
  • Safety controls - CloudFormation automates and manages the provisioning and updating of your infrastructure. There are no manual controls or steps that could lead to mistakes.
  • Dependency management - During stack management activities, AWS CloudFormation automatically maintains dependencies between your resources.

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Ques. 4): What may AWS CloudFormation be used for by developers?


Developers may use a simple, declarative language to deploy and update compute, database, and many other resources, abstracting away the complexities of specific resource APIs. AWS CloudFormation is designed to manage resource lifecycles in a consistent, predictable, and secure manner, including automatic rollbacks, state management, and resource management across accounts and regions. Multiple ways to generate resources have been added recently, including using the AWS CDK for higher-level languages, importing existing resources, detecting configuration drift, and a new Registry that makes it easy to construct unique types that inherit many basic CloudFormation features.

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Ques. 5): Is Amazon EC2 tagging supported by AWS CloudFormation?


Yes. AWS templates can be labelled with Amazon EC2 resources that support the tagging capability. Template parameters, other resource names, resource attribute values (e.g. addresses), or values derived by simple functions can all be used as tag values (e.g., a concatenated a list of strings). CloudFormation automatically assigns the name of the CloudFormation stack to Amazon EBS volumes and Amazon EC2 instances.

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Ques. 6): In AWS CloudFormation, what is a circular dependency? What can be done about it?


An interleaved reliance exists between two resources.

Resource X relies on Resource Y, and Resource Y relies on Resource X.

Because AWS CloudFormation is unable to clearly establish which resource should be produced first in this circumstance, you will receive a circular dependency error.

Interactions between services that make them mutually dependent can produce the AWS CloudFormation circular dependence.

Because AWS CloudFormation is unable to properly decide which resource should be produced first when two are reliant on one another, we will receive a circular dependency error.

The first step is to look over the resources listed and ensure that AWS CloudFormation can figure out what resource order to use.

Add a DependsOn attribute to resources that depend on other resources in your template to fix a dependency error.

We can use DependsOn to express that a particular resource must be produced before another.

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Ques. 7): What is the difference between a resource and a module?


A Resource Type is a code package that contains provisioning logic and allows you to manage the lifecycle of a resource, such as an Amazon EC2 Instance or an Amazon DynamoDB Table, from creation to deletion while abstracting away difficult API interactions. Resource Types include a schema that defines a resource's shape and properties, as well as the logic required to supply, update, delete, and describe it. A Datadog monitor, MongoDB Atlas Project, or Atlassian Opsgenie User are examples of third-party Resource Types in the CloudFormation Public Registry.

Modules are reusable building elements that can be used in numerous CloudFormation templates and are treated similarly to native CloudFormation resources. These building blocks can be used to create common patterns of application design for a single resource, such as best practises for defining an Amazon Elastic Compute Cloud (Amazon EC2) instance, or several resources.

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Ques. 8): Is there a list of sample templates I can use to get a feel for AWS CloudFormation?


Yes, CloudFormation includes sample templates that you may use to try out the service and learn more about its features. Our sample templates show how to connect and use numerous AWS resources simultaneously while adhering to best practises for multiple Availability Zone redundancy, scaling out, and alarming. To get started, simply go to the AWS Management Console, click Create Stack, and follow the instructions to choose and run one of our samples. Select your stack in the console after it has been generated and look at the Template and Parameter tabs to see the details of the template file that was used to create the stack. On GitHub, there are also some sample templates.

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Ques. 9): What distinguishes AWS CloudFormation from AWS Elastic Beanstalk?


AWS CloudFormation allows you to provision and describe all of your cloud environment's infrastructure resources. AWS Elastic Beanstalk, on the other hand, provides an environment that makes it simple to deploy and run cloud applications.

AWS CloudFormation caters to the infrastructure requirements of a wide range of applications, including legacy and existing business applications. AWS Elastic Beanstalk, on the other hand, is used in conjunction with developer tools to assist you manage the lifespan of your applications.

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Ques. 10): What happens if one of the resources in a stack is unable to be created?


The automatic rollback on error option is enabled by default. If all individual operations succeed, CloudFormation will only construct or update all resources in your stack. If they don't, CloudFormation resets the stack to its last known stable state.

For example, if you mistakenly exceeded your Elastic IP address limit, or if you don't have access to an EC2 AMI you're trying to execute. This functionality allows you to rely on the fact that stacks are constructed completely or partially, making system administration and layered solutions built on top of CloudFormation easier.

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Ques. 11): What makes AWS different from third-party resource providers?

The origin of AWS and third-party resource providers is the key distinction. Amazon and AWS create and maintain AWS resource providers to manage AWS resources and services. Three AWS resource providers, for example, assist you in managing Amazon DynamoDB, AWS Lambda, and Amazon EC2 resources. AWS::DynamoDB::Table, AWS::Lambda::Function, and AWS::EC2::Instance are among the resource types available through these providers. Visit our documentation for a complete list of references.

Another corporation, organisation, or developer community creates third-party resource providers. They can assist you in managing AWS and non-AWS resources, such as AWS application resources and non-AWS SaaS software services like monitoring, team productivity, issue management, or version control management tools.

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Ques. 12): How does AWS Cloud Pipeline interact with CloudFormation?


You can use AWS CodePipeline to trigger a Cloud Formation template to run in the deployment phase.

The pipeline has following stages:

Source phase: Fetch the latest commit.

Build phase: Build the code into a docker image and push it to ECR.

Deploy phase: Take the latest docker image from ECR, deploy it to ECS

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Ques. 13): On top of CloudFormation, what does AWS Serverless Application Model offer?


The AWS Serverless Application Model is an open-source architecture for creating serverless apps on Amazon Web Services.

AWS SAM includes a template for defining serverless applications.

AWS CloudFormation allows you to design a template that describes your application's resources and manages the stack as a whole.

You construct a template that outlines all of the AWS resources you need, and AWS CloudFormation handles the rest of the provisioning and configuration.

AWS SAM is a template language extension for AWS CloudFormation that allows you to design serverless AWS Lambda apps at a higher level.

It aids CloudFormation in the setup and deployment of serverless applications.

It automates common tasks such as function role creation, and makes it easier to write CloudFormation templates for your serverless applications.

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Ques. 14): What is the Public Registry for AWS CloudFormation?

Answer: The CloudFormation Public Registry is a new searchable and maintained catalogue of extensions that includes resource types (provisioning logic) and modules provided by APN Partners and the developer community. Anyone can now publish resource types and Modules on the CloudFormation Public Registry. Customers may quickly find and use these public resource types and modules, which eliminates the need for them to construct and maintain them themselves.

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Ques. 15): What is the relationship between the CloudFormation Public Registry and the CloudFormation Registry?


When the CloudFormation Registry first launched in November 2019, it had a private listing that allowed customers to customise CloudFormation for their own use. The Public Registry adds a public, searchable, single destination for sharing, finding, consuming, and managing Resource Types and Modules to the CloudFormation Registry, making it even easier to create and manage infrastructure and applications for both AWS and third-party products.

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Ques. 16): Is it possible to handle individual AWS resources within an AWS CloudFormation stack?


Yes, you certainly can. CloudFormation does not get in the way; you keep complete control over all aspects of your infrastructure and can continue to manage your AWS resources with all of your existing AWS and third-party tools. We advocate using CloudFormation to manage the modifications to your resources because it can allow for extra rules, best practises, and compliance controls. This method of managing hundreds or thousands of resources across your application portfolio is predictable and regulated.

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Ques. 17): What is the Cost of AWS CloudFormation?


Using AWS CloudFormation with resource providers in the AWS::*, Alexa::*, and Custom::* namespaces incurs no additional cost. In this case, you pay the same as if you had manually established AWS resources (such as Amazon EC2 instances, Elastic Load Balancing load balancers, and so on). There are no minimum payments or needed upfront commitments; you only pay for what you use, when you use it.

You will be charged each handler operation if you use resource providers with AWS CloudFormation outside of the namespaces listed above. Create, update, delete, read, or list activities on a resource are handled by handler operations.

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Ques. 18): In a Virtual Private Cloud (VPC), can I create stacks?


Yes. VPCs, subnets, gateways, route tables, and network ACLs may all be created with CloudFormation, as well as resources like elastic IPs, Amazon EC2 instances, EC2 security groups, auto scaling groups, elastic load balancers, Amazon RDS database instances, and Amazon RDS security groups.

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Ques. 19): Is there a limit on how many templates or layers you can have?


See Stacks in AWS CloudFormation quotas for more information on the maximum number of AWS CloudFormation stacks you can construct. Fill out this form to request a higher limit, and we'll get back to you within two business days.

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Ques. 20): Do I have access to the Amazon EC2 instance or the user-data fields in the Auto Scaling Launch Configuration?


Yes. Simple functions can be used to concatenate string literals and AWS resource attribute values and feed them to user-data fields in your template. Please see our sample templates for more information on these simple functions.

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