Short answer: Duplicating allocated public addresses is a bad idea.
Slightly longer answer: Leaving aside the routing issues for the moment, it's not safe to assume that you will never need to reach this machine from some place other than a directly attached cable, or that public or private address allocations are static and will never change.
The remote-access issues are obvious: The global Internet thinks 143.166/16 is in one place, and you want it to be in another. Routers won't go to your machine.
And ownership could change. Even if this address weren't assigned to Dell, it could be allocated to them in the future. Dell does have this address today, but someone else might tomorrow, with a different route. Who knows? Your organization might even buy that address block, with even more routing adventures.
Bottom line: Don't assume duplicate IPs can safely be walled off forever.
As for the routing, your wired interface would prefer the local address over Dell's. Your wired interface would send an ARP request for that address and get it directly from the industrial machine, no gateway required. Thereafter, packets destined to that address would use the destination MAC address of the industrial machine.
That will work fine as you only use a cable for access, and as long as you never need to reach this machine from someplace else, and as long as the global routing table remains static.
That's a lot of ifs. You're better off avoiding the issue by using either a unique public address or something out of the private address pool.
Private IPv4 addresses are defined by RFC1918, in which you will find:
Because private addresses have no global meaning, routing information
about private networks shall not be propagated on inter-enterprise
links, and packets with private source or destination addresses
should not be forwarded across such links. Routers in networks not
using private address space, especially those of Internet service
providers, are expected to be configured to reject (filter out)
routing information about private networks. If such a router receives
such information the rejection shall not be treated as a routing
protocol error.
Without NAT/PAT, the ICMP packet will be dropped by your ISP router. Most of the time, it will be silently drop, but you may have some ICMP message back, depending of the configuration your ISP made.
To have a successful ping reply from an Internet host to a echo request originated by a private IP address there's no other option than NAT/PAT.
Best Answer
A PC in a private IP range can't be acccesed from the public internet.
Devices in private range connecting to internet use a proxy or router/NAT device that replaces the local source IP for a single public IP address that redides in your router/NAT.
However, you can make an exception to that, opening a port in the router and allowing that traffic directed to your public IP adddress and that specific port (for example,
80) get through the router and finally to your PC.Now your PC is public at least on port
80. Internet knows how to get to your PC using the public address and the router translate that public Ip to the private that your device uses.An example:
Your PC has the private IP address
192.168.2.3and is connected to an internet router that has the public IP54.239.25.200.Now, if you open the port
80in the router then anyone in the public internet could connect to your PC using the URL http://54.239.25.200:80The public internet doesn't know your private IP, they know your public IP address.