So a number of websites I use (Salesforce, Lastpass, others) require me to use a PIN to verify when I log in from a new machine - they send a text to my cell phone, I enter the code, all is good.
However, at work today I moved my desktop from one office to another, and every website that requires a PIN is now asking me for a PIN. Same computer, same router/network, same method of connection… but now the intertubes thinks it’s a different machine.
Why?
You may have a different IP number.
If it’s a hardwired ethernet connection, it’s almost definitely a different IP address.
What everyone else said. You may be on the same office network, but to the outside world you’re now coming from a different IP, because your new office location has a different network gateway to the outside world.
It doesn’t have to be a different IP (and I’m guessing it actually isn’t, since most businesses use an internal NAT device and the outside world will only see the IP of your router). At home I had to reinstall my OS. My profile was backed up, I use a static IP address, everything should have been the same, yet web sites thought I had a different PC.
The thing is that web browsing is a 2-way process and your browser tells a web site who you are. I’m guessing that each installation of a browser has a unique ID being broadcast so a site assumes your PC is different when you’re using a different installation of that browser.
None of that applies if all the OP did was move his machine from one place to another.
Heck, I get asked to authorize my “new computer” if I just leave it off for a couple days. As others have said, it’s probably IP changes or (in very modern computers) the location services reporting that the device is in a different physical location.
I used to get the latter sometimes, because the WiFi networks visible at one end of the house were different from the ones at the other end, and somebody must have had a bad location entry in their database, since it would think I’d moved about three miles (my house was not that big).
Or the OP cleaned his cookies out. But I’d go with a different IP appearing to the outside world.
Your computer will ask the network for an address and it will be assigned one, like 192.168.56.102. You can view this with various commands on your computer. However, the outside world may not see that exact address. When your computer goes to the outside world, it goes through a router which may contact the remote computer on your behalf. The remote computer or website will see this external address. You can visit a website like whatismyip.com and it will show you what it sees as your IP address. Generally, the website will see a different address than your computer knows itself as.
If you moved computers to a new office, this new office may go through a different router and the outside websites may see a different address. Your computer could actually have the same address (192.168.56.102) in both offices, but because of how they get to the outside world, the outside world would see them as different.
You can test this by going to the whatsmyip.com website from each office and see if the addresses are the same or different.
Misread the OP, I thought he’d said he’d moved to a DIFFERENT computer. :o
It could be the IP as others suggested but I’m still doubtful, because these sites would be crazy for someone with a laptop. I can’t see a professional website being built that way.
They are built exactly that way, and this is what I go through when sharing my laptop between work and home networks. The whole point is to make sure people are not using potentially insecure networks to access sensitive sites, or to ensure that your laptop or portable hasn’t been stolen.
Could apply. New office location is on different VLAN serviced by different DHCP server.
New office uses a different proxy for load-balancing or log-file management
Restarting the computer clears the cache and/or cookies
User did something that he/she doesn’t remember/not saying.
I vote for last one.
I get a new DHCP IP every day when I reboot. Basing authentication on IP would be maddening, but maybe they try to keep it semi-sane by only looking at the first three octets?
Is that because of some weird way they have your DHCP server set up?
Do you work in I.T.?
I do actually.
I can tell, so do I.
It was a work computer that I just got. Set it up, got it ready for work and a couple of days later had to move the thing, requiring me to redo a number of security steps that I had just done before.
Appreciate the answers, everybody - it just struck me as being a little bit too security-conscious and I was curious as to why the mere act of moving a piece of physical equipment 15 feet requires servers across the world to demand that I verify who I was.
I also have nothing to do with the IT here, so I can’t tell you if my IP is static, dynamic, or etched in diamond, or what router we use or anything.
Possibly. It was a 10 minute operation and, as I said, I have no authority over the IT here. But, really, all I did was disconnect a box, move it into the next office, reconnect it, and start it up again. No intermediate steps, unless bathroom breaks matter. 
[QUOTE=manson1972]
(About getting a new IP every day) Is that because of some weird way they have your DHCP server set up?
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Probably more largeness than weirdness. With about 450,000 computers and 16,000 servers in the enterprise, would you want to keep up with assigning permanent IPs to everyone? Also, I come in on a VPN that only allows a connection to be held for 24 hours, so it would be fairly unlikely to keep the same IP day after day.