Ancient DNS Lore

Test yourself on the arcana of the DNS protocol

This quiz was given at the July 2018 ICANN DNS Symposium. Answers were determined by Ondřej Surý of ISC with Roy Arends of ICANN. The purpose of the quiz is to illustrate the complexity in the DNS as a result of the accumulation of requirements, record types and exceptions over the years.

There is no prize, but at the end, you will see what you got right and what you missed. Most of the questions have more than one possible correct answer. At the ICANN DNS Symposium, the maximum number of correct answers anyone got was 13.

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1. What is the MAILA resource record type?

Not an actual RRTYPE

Query type which returns MB, MG, MR and MINFO records

Query type which returns MF and MD records

Word “MAILER” in #gangsta grammar

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2. What is the WKS resource record type?

A Workstation Resource Record

A Well-Known Service Description record

They serve no known useful function, except internally among LISP machines

Caused by alcohol abuse

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3. What is MAILB resource record type?

Not formally obsoleted

Query type which returns MB, MG, MR and MINFO records

Query type which returns MF and MD records

Inspiration for the “You’ve Got Mail” movie

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4. What is a NULL resource record?

Has RDATA that’s 65535 octets or less

Has RDATA that’s NULL (0 octets)

Not allowed in master files

Declared EXPERIMENTAL in RFC1035

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5. GSS-TSIG...?

Uses SIG(0) to establish secret keys

Used to establish security context

Uses TKEY to establish secret keys

The server MUST not generate a signed response to an unsigned request under any circumstances.

Question Title

6. Which of these is true about the TKEY resource record?

Uses Elliptic-curve Diffie-Hellman for key-exchange

Uses Diffie-Hellman key-exchange

Misspelled T-KEY, a rapper and hip-hop artist

Secret Key Establishment for DNS

Question Title

7. What does “Transactional Security” in the IANA DNSSEC table mean?

The algorithm can be used for DNS over TLS

It has a meaning only in DNSKEY records

Algorithm can be used for SIG(0)

Has a meaning only in KEY records

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8. What is a reasonable default EDNS(0) size?

4096

Slightly less than 1280 (IPv6 minimum fragment size)

Around 1500 (ethernet frame size)

Only Geoff Huston knows

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9. What is the "RP" resource record?

Reverse Proxy record

Responsible Person record

RP records are used in IPoAC

None of the above

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10. Why was 512 octets chosen as the maximum DNS msg size?

To mess with future generations

To be less than minimum IPv4 fragment

To be less than minimum IPv4 packet size

512 octets should be enough for everyone

Question Title

11. We are working hard to simplify BIND9 and remove some of the complexity that has accreted over the years. You can read about it on our blog.
Feel free to leave a comment here if you are motivated to do so. We will read them.

Question Title

1. What is the MAILA resource record type?

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2. What is the WKS resource record type?

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3. What is MAILB resource record type?

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4. What is a NULL resource record?

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5. GSS-TSIG...?

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6. Which of these is true about the TKEY resource record?

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7. What does “Transactional Security” in the IANA DNSSEC table mean?

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8. What is a reasonable default EDNS(0) size?

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9. What is the "RP" resource record?

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10. Why was 512 octets chosen as the maximum DNS msg size?

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11. We are working hard to simplify BIND9 and remove some of the complexity that has accreted over the years. You can read about it on our blog. Feel free to leave a comment here if you are motivated to do so. We will read them.

11. We are working hard to simplify BIND9 and remove some of the complexity that has accreted over the years. You can read about it on our blog.
Feel free to leave a comment here if you are motivated to do so. We will read them.