I know it can take up to a few days for DNS changes to take effect, but this has me baffled, maybe somone can offer a plausible explanation..
$ wget http://***OLDIP***/ -O oldserver.html
--2012-07-25 16:31:19-- http://***OLDIP***/
Connecting to ***OLDIP***:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: `oldserver.html'
[ <=> ] 18,359 --.-K/s in 0.01s
2012-07-25 16:31:20 (1.61 MB/s) - `oldserver.html' saved [18359]
$ wget http://***NEWIP***/ -O newserver.html
--2012-07-25 16:31:35-- http://***NEWIP***/
Connecting to ***NEWIP***:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: `newserver.html'
[ <=> ] 18,112 --.-K/s in 0.01s
2012-07-25 16:31:35 (1.27 MB/s) - `newserver.html' saved [18112]
$ wget http://***HOSTNAME***/ -O dns.html
--2012-07-25 16:31:49-- http://***HOSTNAME***/
Resolving ***HOSTNAME***... ***NEWIP***
Connecting to ***HOSTNAME***|***NEWIP***|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 18361 (18K) [text/html]
Saving to: `dns.html'
100%[===================================================================================================================================================================================================>] 18,361 --.-K/s in 0.01s
2012-07-25 16:31:49 (1.26 MB/s) - `dns.html' saved [18361/18361]
Now the above is exactly waht I would expect after a DNS change, so no surprise there, until I tell you that oldserver.html and dns.html have the same output, and newserver.html, differs!
Since HOSTNAME is resolved to NEWIP, how on earth can it have the output of the old server?
Completely baffled.
EDIT: More confusion:
$ wget http://***HOSTNAME***/ -O dns.html
--2012-07-25 17:23:45-- http://***HOSTNAME***/
Resolving ***HOSTNAME*** (***HOSTNAME***)... ***NEWIP***
Connecting to ***HOSTNAME*** (***HOSTNAME***)|***NEWIP***|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 18361 (18K) [text/html]
Saving to: `dns.html'
100%[===================================================================================================================================================================================================>] 18,361 --.-K/s in 0s
2012-07-25 17:23:45 (142 MB/s) - `dns.html' saved [18361/18361]
$ sudo vim /etc/hosts
$ wget http://***HOSTNAME***/ -O dns.html
--2012-07-25 17:24:53-- http://***HOSTNAME***/
Resolving ***HOSTNAME*** (***HOSTNAME***)... 127.0.0.1
Connecting to ***HOSTNAME*** (***HOSTNAME***)|127.0.0.1|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 18361 (18K) [text/html]
Saving to: `dns.html'
100%[===================================================================================================================================================================================================>] 18,361 --.-K/s in 0s
2012-07-25 17:24:53 (144 MB/s) - `dns.html' saved [18361/18361]
I did this on the NEW server. As you see both requests output 18361 bytes, while the correct output (newserver.html) should output 18112...
OUTPUT wget -S
$ wget -S http://***HOSTNAME***/
--2012-07-25 17:19:51-- http://***HOSTNAME***/
Resolving ***HOSTNAME***... ***NEWIP***
Connecting to ***HOSTNAME***|***NEWIP***|:80... connected.
HTTP request sent, awaiting response...
HTTP/1.1 200 OK
Date: Wed, 25 Jul 2012 15:19:45 GMT
Server: Apache/2.2.22 (Ubuntu)
Last-Modified: Tue, 24 Jul 2012 08:13:21 GMT
Accept-Ranges: bytes
Content-Length: 18361
Vary: Accept-Encoding
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html; charset=UTF-8
Length: 18361 (18K) [text/html]
Saving to: `index.html.1'
100%[===================================================================================================================================================================================================>] 18,361 --.-K/s in 0.01s
2012-07-25 17:19:51 (1.47 MB/s) - `index.html.1' saved [18361/18361]
This is clearly the NEW server, old server ran CentOS.
EDIT
Sorry people. It appears the problem is with WordPress.
Exactly to AVOID this type of issues I disabled all forms of caching. Oddly enough when I re-enabled them, I saw the new content. Very, very, very odd.