Consider the following scenario:
Id 
First Name 
Last Name 
1
John
Abraham
I have stored this data in a DynamoDB table. After running an update, I change the Last Name from “Abraham” to “Mathew”. When John reads his data immediately after the update, he still sees his Last Name as Abraham rather than Mathew. What is the possible reason?

Answer options:

A.DynamoDB takes 1 second to ensure consistency across all its copies of data.
B.By default DynamoDB reads are eventually consistent.
C.DynamoDB does not support strongly consistent reads.
D.All ofA, B & C

Answer: B
DynamoDB chooses Performance over Consistency while delivering reads. Using this model, during a read, DynamoDB will look for the nearest & most available storage location for fulfilling the read request. DynamoDB stores three geographically distributed replicas of each table. It may so happen that the storage location where DynamoDB performs the read would not have been updated with the latest data. Strong consistency involves multiple reads to ensure that the latest update is always available sacrificing Performance.
Option A is incorrect. Consistency across DynamoDB does reach within 1 second. But it is the DynamoDB’s read model rather than the lag that causes stale data to appear.
Option B is CORRECT. The default read model supported by DynamoDB is an “Eventually Consistent” one as described above.
Option C is incorrect. DynamoDB supports strongly consistent reads but by default it uses eventually consistent reads.
Option D is incorrect because of the reasons discussed above.
Reference:
https://youtu.be/SqMevk3n3EQ
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadConsistency.html