The network is usually dated to the month its first hardware went in, which is not when anything was transmitted. The transmission itself is logged at 10:30 pm local time, so reading the log in UTC moves the answer to the next day.
Both traps are recorded in the challenge rather than hidden, and the question fixes the time zone so only one date survives.
The question as published
In 1969 a student programmer in Los Angeles transmitted the first characters to a host at a research institute several hundred miles north, at 10:30 pm local time. On what date, in local Pacific time, did that transmission take place?
- Answer
- 29 October 1969
- Confidence
- High — logged timestamp corroborated by an institutional timeline
Sources opened and read
ARPANET
Wikipedia • Reference database • Secondary
Gives both the local and UTC timestamps, which is exactly the ambiguity the benchmark tests.
Open sourceBrief History of the Internet
Internet Society • Technical organisation • Primary
Written by people directly involved in the work; it dates the installation but not the first message, which keeps the decoy month in play.
Open sourceTimeline of Computer History — 1969
Computer History Museum • Museum record • Secondary
A curated institutional record that narrows the month without giving the day, so it corroborates without leaking the answer.
Open source
Searches that were run
when was ARPANET created
Google • 4 September 2026 • Answer exposed: No
Returns 1969 and the September installation, not the transmission date.
first message sent over ARPANET date
Google • 4 September 2026 • Answer exposed: Yes
Exposes 29 October 1969 in the snippet.
UCLA Stanford Research Institute host to host transmission 1969 programmer log
Google • 4 September 2026 • Answer exposed: No
Returns anniversary coverage and archival material; the day is confirmed only after opening a record.
ARPANET first message 30 October 1969 UTC
Google • 4 September 2026 • Answer exposed: Yes
Surfaces the alternative UTC date used by some accounts.
What the investigation showed
What made the question difficult
Three dates are in circulation: the September hardware installation, the 29 October local transmission and the 30 October UTC equivalent.
Which searches failed
Queries about when the network was 'created' returned the September installation and never reached the transmission log.
Which source proved decisive
The log caption that carries both the Pacific and UTC timestamps, because it makes the discrepancy explicit instead of leaving it to be inferred.
How ambiguity was removed
The question names the time zone, so only one of the two defensible dates survives.
What an AI browsing agent might get wrong
Answering September 1969, or returning 30 October 1969 by quoting the UTC conversion without noticing the question specifies local time.
Remaining limitations
The decisive detail here rests partly on an encyclopaedia article; a scan of the original IMP log page would make the chain fully primary.
Recommended future improvements
Locate the digitised UCLA log sheet and cite the handwritten entry directly.
Read the full case study
The complete record — clue matrix, evidence cards, validation log and the structured JSON output — is published on the case study page.
Open Computing History Benchmark