SNS notification types (email, SMS, Lambda) in AWS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Amazon SNS used for?

Amazon SNS (Simple Notification Service) is used to send messages or notifications to multiple subscribers through different protocols like email, SMS, or Lambda functions.

beginner

How does SNS send notifications to email subscribers?

SNS sends notifications to email subscribers by sending an email message to the subscribed email address when a message is published to the topic.

beginner

What is required to send SMS notifications using SNS?

To send SMS notifications, the subscriber must be a valid phone number, and the SNS topic must support SMS protocol. AWS handles the delivery to the phone via SMS.

intermediate

How does SNS trigger a Lambda function?

SNS can trigger a Lambda function by invoking it directly when a message is published to the SNS topic, allowing automated processing of the message.

intermediate

What are the benefits of using Lambda as an SNS subscriber?

Using Lambda as an SNS subscriber allows automatic, serverless processing of messages, enabling custom logic, data transformation, or integration with other AWS services without managing servers.

Which protocol does SNS NOT support for notifications?

A FTP

B SMS

C Lambda

D Email

SNS supports Email, SMS, and Lambda protocols but does not support FTP for notifications.

What must a user do to receive SNS email notifications?

A Create an IAM user

B Just provide the email address without confirmation

C Subscribe and confirm the subscription via email

D Enable SMS on the email

Users must subscribe and confirm the subscription by clicking a link sent to their email to start receiving SNS notifications.

What happens when SNS publishes a message to a Lambda subscriber?

A Lambda sends an email

B Lambda function is invoked automatically with the message

C SNS stores the message in S3

D Nothing happens

SNS automatically invokes the subscribed Lambda function with the published message as input.

Which of these is a valid SNS notification type?

A Email

B FTP

C HTTP

D Both A and C

SNS supports multiple protocols including Email and HTTP, but not FTP.

To send SMS notifications via SNS, what is required?

A A valid phone number subscribed to the topic

B An email address

C A Lambda function

D An S3 bucket

SNS sends SMS notifications to valid phone numbers subscribed to the topic.

Explain how SNS can send notifications using email, SMS, and Lambda.

Think about how each subscriber type receives or processes the message.

Describe the benefits of using Lambda as a subscriber in SNS notifications.

Consider what Lambda adds beyond simple message delivery.

Practice

1. Which of the following is NOT a valid protocol for an AWS SNS subscription?

easy

A. email

B. sms

C. lambda

D. ftp

Solution

1. Step 1: Review SNS supported protocols

   AWS SNS supports protocols like email, sms, and lambda for subscriptions.

2. Step 2: Identify unsupported protocol

   FTP is not supported as a protocol for SNS subscriptions.

3. Final Answer:

   ftp -> Option D

4. Quick Check:

   Supported protocols exclude ftp [OK]

Hint: Remember SNS supports email, sms, lambda but not ftp [OK]

Common Mistakes:

• Confusing FTP as supported protocol
• Thinking HTTP is the only protocol
• Mixing SNS with S3 protocols

2. Which is the correct way to specify an SMS subscription protocol in AWS SNS?

easy

A. Protocol: 'sms', Endpoint: '[e-mail]'

B. Protocol: 'email', Endpoint: '[phone]'

C. Protocol: 'sms', Endpoint: '[phone]'

D. Protocol: 'lambda', Endpoint: '[phone]'

Solution

1. Step 1: Understand protocol and endpoint types

   For SMS, protocol must be 'sms' and endpoint is a phone number with country code.

2. Step 2: Match correct protocol and endpoint

   Protocol: 'sms', Endpoint: '[phone]' correctly uses 'sms' protocol and a phone number endpoint.

3. Final Answer:

   Protocol: 'sms', Endpoint: '[phone]' -> Option C

4. Quick Check:

   SMS needs phone number endpoint [OK]

Hint: SMS protocol requires phone number endpoint format [OK]

Common Mistakes:

• Using email as protocol for SMS
• Using email address as SMS endpoint
• Using lambda protocol with phone number

3. Given this AWS SNS subscription code snippet:

sns.subscribe({
  Protocol: 'lambda',
  Endpoint: 'arn:aws:lambda:us-east-1:123456789012:function:ProcessMessage'
});

What happens when a message is published to this SNS topic?

medium

A. The Lambda function 'ProcessMessage' is invoked with the message payload.

B. The message is sent as an SMS to the Lambda function ARN.

C. The message is sent as an email to the Lambda function.

D. The subscription will fail because Lambda cannot be an endpoint.

Solution

1. Step 1: Identify protocol and endpoint meaning

   Protocol 'lambda' means SNS invokes the specified Lambda function ARN when a message is published.

2. Step 2: Understand message delivery behavior

   The Lambda function 'ProcessMessage' is called with the message payload as input.

3. Final Answer:

   The Lambda function 'ProcessMessage' is invoked with the message payload. -> Option A

4. Quick Check:

   Lambda protocol triggers function invocation [OK]

Hint: Lambda protocol triggers function call, not email or SMS [OK]

Common Mistakes:

• Thinking Lambda receives email or SMS
• Assuming subscription fails
• Confusing endpoint ARN with phone/email

4. You created an SNS subscription with protocol 'email' but the subscriber never receives messages. What is the most likely cause?

medium

A. The email address was not confirmed by the subscriber.

B. The SNS topic does not support email protocol.

C. The subscription endpoint was set to a phone number.

D. Lambda function is not attached to the subscription.

Solution

1. Step 1: Understand email subscription confirmation

   Email subscriptions require the recipient to confirm by clicking a link in a confirmation email.

2. Step 2: Identify common cause of no delivery

   If the email is not confirmed, SNS will not send notifications to that address.

3. Final Answer:

   The email address was not confirmed by the subscriber. -> Option A

4. Quick Check:

   Email subscriptions need confirmation [OK]

Hint: Email subscriptions require confirmation before delivery [OK]

Common Mistakes:

• Assuming SNS does not support email
• Confusing phone number as email endpoint
• Expecting Lambda involvement in email subscription

5. You want to send an SMS notification and also trigger a Lambda function whenever a message is published to an SNS topic. How should you configure the subscriptions?

hard

A. Create one subscription with protocol 'email' and endpoint as phone number, and another with protocol 'lambda' and endpoint as Lambda ARN.

B. Create one subscription with protocol 'sms' and endpoint as phone number, and another with protocol 'lambda' and endpoint as Lambda ARN.

C. Create one subscription with protocol 'lambda' and endpoint as phone number, and another with protocol 'sms' and endpoint as Lambda ARN.

D. Create one subscription with protocol 'sms' and endpoint as Lambda ARN, and another with protocol 'lambda' and endpoint as phone number.

Solution

1. Step 1: Understand protocol and endpoint matching

   SMS protocol requires a phone number endpoint; Lambda protocol requires Lambda function ARN.

2. Step 2: Configure two subscriptions correctly

   Create one subscription with protocol 'sms' and phone number endpoint, and another with protocol 'lambda' and Lambda ARN endpoint.

3. Final Answer:

   Create one subscription with protocol 'sms' and endpoint as phone number, and another with protocol 'lambda' and endpoint as Lambda ARN. -> Option B

4. Quick Check:

   Match protocol to correct endpoint type [OK]

Hint: Match SMS to phone number, Lambda to function ARN [OK]

Common Mistakes:

• Mixing endpoints and protocols
• Using email protocol for SMS
• Assigning Lambda ARN as SMS endpoint