DynamoDB replicates data in three different facilities within a region. When you read data from DynamoDB, by default they are eventually consistent reads and hence you may not always see the latest data. You can opt for strongly consistent reads at twice the cost of eventually consistent reads.

One RCU can be used for one strongly consistent read per second or two eventually consistent reads per second, for an item up to 4 KB in size. One WCU can be used for one write per second for an item up to 1 KB in size.