Errors in timestamp-based HTTP header values

tion in 1982. Our focus is information technology that is relevant to the technical strategy of the Corporation, and that has the potential to open new business opportunities. Research at WRL includes Internet protocol design and implementation, tools for binary optimization, hardware and software mechanisms to support scalable shared memory, graphics VLSI ICs, hand-held computing, and more. Our tradition at WRL is to test our ideas by extensive software or hardware prototyping. We publish the results of our work in a variety of journals, conferences, research reports, and technical notes. This document is a research report. Research reports are normally accounts of completed research and may include material from earlier technical notes. We use technical notes for rapid distribution of technical material; usually this represents research in progress. You can also request reports and notes via electronic mail. For detailed instructions, put the word ''Help'' in the Subject line of your message, and mail it to: Abstract Many of the caching mechanism in HTTP, especially in HTTP/1.0, depend on header fields that carry absolute timestamp values. Errors in these values could lead to undetected cache incoherence, or to excessive cache misses. Using an extensive proxy trace, we looked for HTTP responses exhibiting several different categories of timestamp-related errors. A significant fraction of these responses have detectable errors in timestamp-based header fields.