I own the domain penkov.id.au. I host a blog using github, with an A record for the subdomain michael.penkov.id.au pointing to the github pages server (204.232.175.78).
bash-3.2$ dig michael.penkov.id.au +nocomments +nocmd +nostats
; <<>> DiG 9.8.3-P1 <<>> michael.penkov.id.au +nocomments +nocmd +nostats
;; global options: +cmd
;michael.penkov.id.au. IN A
michael.penkov.id.au. 86400 IN A 204.232.175.78
penkov.id.au. 14399 IN NS ns1.linode.com.
penkov.id.au. 14399 IN NS ns5.linode.com.
penkov.id.au. 14399 IN NS ns4.linode.com.
penkov.id.au. 14399 IN NS ns2.linode.com.
penkov.id.au. 14399 IN NS ns3.linode.com.
ns1.linode.com. 62648 IN A 69.93.127.10
ns1.linode.com. 136520 IN AAAA 2600:3c00::a
ns2.linode.com. 67499 IN A 65.19.178.10
ns2.linode.com. 122812 IN AAAA 2600:3c01::a
ns3.linode.com. 124971 IN A 75.127.96.10
ns3.linode.com. 133162 IN AAAA 2600:3c02::a
ns4.linode.com. 96383 IN A 207.192.70.10
ns4.linode.com. 904 IN AAAA 2600:3c03::a
ns5.linode.com. 44638 IN A 109.74.194.10
ns5.linode.com. 56329 IN AAAA 2a01:7e00::a
Recently (around a month ago, maybe more), I've found that all requests to the subdomain (e.g. http://michael.penkov.id.au/blog/2014/01/02/reinventing-the-wheel.html) are met with a 302 response. This is a problem for sites like facebook.com, which don't bother accessing that URL to provide previews. Github notes that 302 redirects are not errors and should be followed, but Facebook apparently ignores that.
I had a look at the request & response headers using Chrome's debugging tools:
Request:
GET /blog/2014/01/02/reinventing-the-wheel.html HTTP/1.1
Host: michael.penkov.id.au
Connection: keep-alive
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8,ja;q=0.6,ru;q=0.4
Cookie: __utma=146715829.533338776.1383309288.1383487335.1383547294.7; __utmz=146715829.1383309288.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=118121621.1819750941.1383609188.1387026971.1388676605.15; __utmb=118121621.11.10.1388676605; __utmc=118121621; __utmz=118121621.1387026971.14.7.utmcsr=facebook.com|utmccn=(referral)|utmcmd=referral|utmcct=/
If-Modified-Since: Thu, 02 Jan 2014 14:38:15 GMT
Response:
HTTP/1.1 302 Found
Connection: close
Pragma: no-cache
cache-control: no-cache
Location: /blog/2014/01/02/reinventing-the-wheel.html
Finally, a sure way to reproduce this problem is to use the Facebook URL debugging tool. Point it at http://michael.penkov.id.au/blog/2014/01/02/reinventing-the-wheel.html to see the problem.
My questions:
- What is causing the redirect? Is it the A-record?
- Where is the redirect actually to? How can I find this out? How can I fix it?
- Can I get rid of the redirect? In other words, how do I get the server to return 200 instead of 302? Other sites with an identical setup (e.g http://mdswanson.com/blog/2013/11/13/some-tools-i-like.html) respond with 200.