by Darius Kazemi, November 4 2019

In 2019 I'm reading one RFC a day in chronological order starting from the very first one. More on this project here. There is a table of contents for all my RFC posts.


RFC-308 is titled “ARPANET Host Availability Data”. It's dated March 13th, 1972 and authored by first-time RFC author Marc Seriff, who is personnel working on the MIT Project MAC Dynamic Modeling Computer Graphics PDP-10.

The technical content

MIT has implemented an automated survey of uptime for ARPANET hosts. Their definition of whether a host is online is whether it is accepting connections on the Initial Connection Protocol. This is a limited definition of “online” but they don't want to unnecessarily flood the network and tie up resources on the various hosts. The survey pings all known hosts once every fifteen minutes, at least while MIT's host is online.

One very cool thing is that you can access the results of the survey program yourself by logging into MIT-DMCG and issuing commands to look at some of the survey statistics. This includes a BEST.SURVEY command that “lists the best of the recent surveys”, which I don't know what it means but it sounds great.


The author is very forthcoming about the limitations of the data that they are collecting. I won't even summarize the data here because frankly the methodology is really suspect (the survey is essentially “how often are remote hosts online while MIT's host is online”). But again, kudos to the author for acknolwedging this in the RFC itself.

To me the important part about this is that they offer the statistics as an ongoing service to anyone who wants to see them. Compare this to the compiled statistics sent out as RFCs every two weeks by BBN. Hopefully BBN will soon move to a system like this.

Further reading

See RFC-186 for more about the Dynamic Modeling Computer Graphics computer.

The author of this RFC, Marc Seriff, would go on to co-found the company that would eventually be known as America Online.

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About me

I'm Darius Kazemi. I'm an independent technologist and artist. I do a lot of work on the decentralized web with ActivityPub, including a Node.js reference implementation, an RSS-to-ActivityPub converter, and a fork of Mastodon, called Hometown. You can support my work via my Patreon.