ISO8583 Foundations Quiz

Test your understanding of ISO8583 message structure, MTIs, message flows, and encoding.

Get every question correct to pass this checkpoint. You can review feedback, revise your answers, and submit again.

1. After transport framing, the course uses the 1987 MTI convention. What does 0420 identify?

Select one answer.

Reversal advice with acquirer origin Authorization response A guaranteed successful reversal A completed settlement

2. What is the purpose of the bitmap in an ISO8583 message?

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To indicate which data elements are present in the message To specify the message routing information To validate the message integrity (checksum) To encrypt the message payload

3. An authorization deadline expires without a response. Which fact is established?

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No authorization can arrive later The issuer definitely rejected it The caller has no answer yet; remote processing is unresolved Sending any reversal proves cancellation

4. You see an MTI of `0101`. How does this differ from `0100`?

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0101 is from the issuer, 0100 is from the acquirer 0101 uses 2003 spec, 0100 uses 1987 spec 0101 is a response, 0100 is a request 0101 is a repeat transmission (retry), 0100 is the first attempt

5. In an ISO8583 message, how do you know if a secondary bitmap (fields 65-128) is present?

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Field 64 contains a special marker Bit 1 of the primary bitmap is set to 1 The MTI version digit is set to 2 The message length exceeds a certain threshold

6. A configured route matches responses by DE11, DE12/13, and DE32. Why retain all these request values?

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A reused STAN alone can collide across time or acquirers DE39 alone uniquely identifies a request A response must always have a new STAN Every network uses exactly these fields

7. You're parsing a message and the primary bitmap is `F2 34 00 01 08 E1 80 00`. Which of these fields is definitely NOT present?

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Field 5 Field 65 (Secondary bitmap field) Field 2 (PAN) Field 3 (Processing Code)

8. In the exercise response-code table, 00 means authorization approved. What does receiving it establish?

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Approval under that profile, not completed clearing That the MAC is valid without verification That the transaction has already settled That all later reversals will succeed

9. Two partners both say ISO8583 but one uses a binary bitmap and the other hex-ASCII. What is needed before exchanging messages?

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An agreed profile defining framing and encodings Assuming printable bytes determine the format Only matching MTI digits Replacing all messages with JSON

10. What does an MTI of `0800` typically represent?

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Reversal request Financial advice Authorization request Network management request (sign-on, echo test, or key exchange)

11. The configured ASCII MTI starts after the transport header. Its bytes are 30 31 30 30 in hexadecimal. Which MTI is represented?

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0100 0x0100 as a two-byte integer 3031 1000

12. Your parser reads the first bytes of a TCP stream as: `00 C8 30 31 30 30 72...`. What's likely happening?

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The message is corrupted The bitmap is malformed There's a 2-byte length header (200 bytes) before the ASCII MTI This is a BCD-encoded MTI

13. What is Field 1 (DE1) in an ISO8583 message?

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The primary bitmap The secondary bitmap (when present) The message type indicator Reserved for future use

14. The course DE3 table defines 01=cash withdrawal, 10=savings, and 20=checking, in transaction/from/to order. What does 011020 mean?

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Cash withdrawal from savings to checking Purchase from checking to savings Refund to a default account Cash withdrawal from credit to checking

15. An amount field (DE4) contains `000000010000` and the currency code (DE49) is `392` (JPY). What's the actual amount?

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100.00 JPY 10.000 JPY 1000.00 JPY 10000 JPY

16. The configured transport uses a two-byte big-endian body length and a four-byte TPDU. For bytes 00 C8 60 00 00 00 30 31 30 30, where does the ASCII MTI start?

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Offset 2 Offset 4 Offset 6 Offset 0

17. A retry reuses an original business identity but has a new transport connection. What should the idempotency store key represent?

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Only the TCP connection Only the amount The profile-defined business operation identity Only the MAC bytes

18. A two-bitmap profile forbids tertiary extension, but the secondary extension bit is set. What should validation do?

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Clear the bit silently Interpret the bit as the amount Read arbitrary remaining bytes as a third bitmap Reject the unsupported extension

19. DE2 declares 20 value bytes, while only 18 bytes remain in the entire frame. What is certain?

Select one answer.

The declared field is truncated The PAN is valid because the bitmap is valid The two missing bytes are zeros The next TCP read must belong to this frame

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