Execution of a block test “retry” in a test environment with each block in the test sequence sent after the tester has determined that the previous block of data packets has met one or more prescribed test criterion. If a block sent by the DUT has not met the test criterion, a retry sequence is initiated to re-test the block. In another embodiment, a block test “retry” is executed where each block in the test sequence is sent and analysis of previously sent blocks is done in parallel with the sending of a subsequent block. If a previous block has not met the test criterion, a retry sequence is initiated whereby the tester and DUT step back to the block that failed to meet the test criterion and retry that block. If the retry meets test criterion, testing continues by resuming with the next untested block in the sequence.