Cache is showing incorrect date

[doc_z]

I found that Google is showing an incorrect date for the cache. The cached page shows

This is G o o g l e's cache of ... as retrieved on 20 Nov 2005 09:20:36 GMT

However, the cache doesn't show current version, but the last modifications were made a month ago.

The header clearly shows

Last-Modified: Thu, 27 Oct 2005 08:58:47 GMT

Therefore, the cache is it least one month old. Has someone else observed this phenomenon?

[oddsod]

There are some weird things happening with G cache at the moment.

[g1smd]

I have an old file (one already indexed) with some content. It was always properly cached and has been for years. I left it on the server, but renamed it by adding a Z to the name while I put up a new (but temporary) version of the page online with the old filename.

The new file contents were reindexed after a few days, and the temporary content stayed online for a few months. The Google cache was also updated to show the new content, and re-cached several times per week during that time.

A few weeks ago, I deleted the temporary page and reinstated the old page (simply by removing the Z from the filename). Google continues to update the cache date every few days (right now it says Nov 25th), but the cache always shows the old temporary content - content that was removed about a month ago.

I assume it simply reads the file date and assumes that nothing has changed. Now that could be open to a lot of abuse: get a page to rank, then change the content to something else - but it continues to rank for the other content.

[doc_z]

I assume it simply reads the file date and assumes that nothing has changed.

As far as I remember, Google is using the "Last-Modified" information. If the page hasn't changed, the old version is used. (I only found this thread [webmasterworld.com].)

[g1smd]

The page did change.

It changed to an earlier date, when I renamed it back.

[Shaundm]

I've had it that the date of the last index has gone back in time... One day would say 20th a few days later would go back to the 5th.

[online]

can someone please clarify.. :) sorry for a silly question, but i never noticed this before.. On the SERPs page next to the URL there's such info as: 25k - 29 Nov 2005 - Cached - Similar pages. However, when I click for a 'cached version', it dates 26 Nov. The next time it would show up 29th. So is this the issue with different datacenters? I used to think that the date by the URL indicates the date of the latest cache. Or is it just the date of the last crawl instead?

[g1smd]

Date by URL is last crawl.

Date in cache is when that copy was actually taken... and sometimes Google has more than one copy of a page maybe a recent one and one from years ago. Sometimes different datacentres have a different cache, and when the cache is updated it doesn't happen in all datacentres at the same time; it takes at least several hours.