Answer - Following is a list of different isolation levels in WCF: o Read Uncommitted: Also known as dirty isolation level. It makes sure that corrupt Data cannot be read. This is the lowest isolation level. o Read Committed: It ensures not to read the data that has been changed by any other application and is not yet committed. It is the default level. o Repeatable Read: It stops the usage of dirt read and non-repeatable read. It states that data fetched through a query will be locked and will not be updated by any other transaction. o Serializable: It does not allow any modification and addition of new data till the transaction is completed. This is considered to be a very restrictive level. o Snapshot: It raises an error on modifying a data that has already been changed by any transaction.