Difference in website display depending on domain

Question

I'm getting slightly different display of a website depending on which URL I use to access it (two different servers, both serving the same files). One looks "thinner" than the other in Firefox 3.0 (no discernible difference in IE)

For example, compare:

http://www.ece.ualberta.ca/support/

and

http://www1.ece.ualberta.ca/support/

This is not a major issue, but I just noticed this and am extremely curious as to what could cause it. Is it some kind of Firefox bug? I haven't yet tried the newest version.

EDIT: My bad for assuming those URL's were actually serving the same content (it's not my server, but I do attend that school). Comparing:

http://www.ece.ualberta.ca/~ecegsa/links.html (it seems this server is down atm) and http://www1.ece.ualberta.ca/~ecegsa/links.html

shows the same issue, but the HTML is identical according to diff run on saved files. I don't see the problem on anything other than FF 3.0 at my work, so I'm guessing it's some idiosyncrasy with that browser. Still curious though.

Answer 1

Looking briefly at those two URLs, they're running different HTML!

For example, http://www.ece.ualberta.ca/support/ has this text:

Windows Vista/7 (volume license) Activation

While http://www1.ece.ualberta.ca/support/ has this text:

Windows Vista (volume license) Activation

I suspect that different HTML accounts for the difference you're seeing.

If these are actually the same servers hosting the same content, this kind of disparity could be caused by intermediate caches (e.g. proxies, CDN's, etc.) refreshing at different rates. For example, if www points to a load-balancing, caching proxy and www1 points directly to the host, this may cause the difference. You might also be seeing a bug or lag in how content is updated to different servers in a load-balanced cluster.