Way to cause connection to a different online server in server farm?

I'm trying to test for IP ranges to open in a firewall, for connection to a provider's web site.
They have many servers and, if you connect thru different PCs you get redirected to one of them.
There seems to be some memory held somewhere that will redirect you to the same server if you connect from the same PC with the same user.
I'd like to be able to go to the site from 1 PC over and over and collect the IP addresses with a packet reader, but there appears to be something that needs to be flushed out each time.

Is there a command line process that can reset this, so that the web site does not recognise the request as being from the same source?

(I don't want to wait a week for the provider to send the IP addresses to me)
Allowing a Fully Qualified Domain Name thru the firewall does not work.

TIA !!
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How about doing an NSLOOKUP of the hostname to see what addresses are registered in DNS for it?


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Paul MacDonaldDirector, Information SystemsCommented:
It may be the server sets a cookie, but more likely you're not waiting long enough for the session to expire.  Most web sites use something like 20 minutes, but all the does is kill the session (in other words, if you closed your browser for 20 minutes, the session would expire) - you'd still have no way to guarantee you hit a different server each time.

It's not clear to me what data you're trying to collect, but is it possible the web site itself could get the data and send it to you on some sort of schedule or trigger?
machine_runAuthor Commented:
The site operators, ADP, are not quick to respond to say the least.
Users are attempting to log into portal.adp.com

I'm having a bear of a time trying to allow this thru the firewall.
This just started happening. They may have moved to an akamai server farm.

So far users can get to the site 50% of the time.
There are still IP Addresses I have to try to find.
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Daniel HelgenbergerCommented:
Ok, let me try. I hope I do you no wrong; and understood it correctly

You are connecting from your computer through your firewall to different web site / service (a big one, like google or facebook or such?). Then, you end up on the same server even if you use  different computers in your network.

This may have to reasons, please let me write an analogy:
Say, you take your car and go on vacation. You have never been there before, you have to use a map had have to take some detours. It takes a long time. On the way back home, you already know the way. It is much faster therefore.
The next year, you remember the the way you want and take the same route (here we go!) - even if there may be a new highway around which you did not know about. So once you learned about the new highway you forget the old route and take the new, better one back.

This is called routing in network terms and works all the same way basically. The map is the routing table and your memory is the routing cache. Imagine the same with your firewall. Since you have only one, the firewall knows the way and always point you to the same server because it is much quicker then to find a new one every time. Not even if you use another computer in your network, because it still asks the same router.

But, you can forget the way you wend any time. In routing this is a cache flush:
ip route flush cache

Open in new window

Would be the command on a unix / linux router (you did not tell us what make/model) the same can be achieved by rebooting it.
To test other ways, just use your smartphone in a cellular network. Since it uses another router, chances are you end up on another server.

Reason number 2:
If it is a big websites my incorporate load balancing among many other things which lets you always end on the same server. This is something you cannot change.
Paul MacDonaldDirector, Information SystemsCommented:
Can you not create a firewall rule that allows access to portal.adp.com?  It has to be done by IP?
machine_runAuthor Commented:

allowing portal.adp.com isn't doing it (at least not all the time)

Allowing *.adp.com was working for at least a year.

Looks like they are redirecting logons to other domains.
Paul MacDonaldDirector, Information SystemsCommented:
Interesting!  And they won't tell you what those other domains are?  That seems shady (or buggy)...

Is there a way to check the router log for the denied connection?  You may get some information that way.  Even PINGing "portal.adp.com" from a machine that can't access the site may tell you what IP that machine is resolving from the host name.
machine_runAuthor Commented:
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