Private IP Addressing

in Network+
Hi, I'm new here, just starting my network+. I'm fluent with PC repair and maintenance and configuring windows but have a very limited knowledge of networking that doesn't stretch far beyond the home router so decided to take this cert.
Anyway, I was wondering if someone can clarify something for me to help me understand the topic of Private IP Addressing a little bit more.
The book i'm reading states that all private IPs should fall into 3 ranges set by RFC 1918, class A 10.0.0.0 - 10.255.255.255 , class B 172.16.0.0 - 172.31.255.255 and class C 192.168.0.0 - 192.168.255.255, which is fine, I had no problem understanding that, but I decided to be nosey at work today on the corporate network and done a quick ipconfig on my workstation expecting to see one of these addresses. The address that came back to me began 149.209.x.x with gateway of 255.255.255.0 which doesn't fit into any of the above. The gateway address also began with 149.209.x.x
What is my IP.com showed the public address starting with 195. so it didn't come from there. If someone could explain to me where this IP range comes from so I can understand bit more that would be great.
Sorry if i'm jumping ahead or missing something obvious, but its thrown me into confusion.
Anyway, I was wondering if someone can clarify something for me to help me understand the topic of Private IP Addressing a little bit more.
The book i'm reading states that all private IPs should fall into 3 ranges set by RFC 1918, class A 10.0.0.0 - 10.255.255.255 , class B 172.16.0.0 - 172.31.255.255 and class C 192.168.0.0 - 192.168.255.255, which is fine, I had no problem understanding that, but I decided to be nosey at work today on the corporate network and done a quick ipconfig on my workstation expecting to see one of these addresses. The address that came back to me began 149.209.x.x with gateway of 255.255.255.0 which doesn't fit into any of the above. The gateway address also began with 149.209.x.x
What is my IP.com showed the public address starting with 195. so it didn't come from there. If someone could explain to me where this IP range comes from so I can understand bit more that would be great.
Sorry if i'm jumping ahead or missing something obvious, but its thrown me into confusion.
Comments
I suspect the op meant subnet mask, rather than gateway (the first time) as they then go on to say the gateway address also began with 149.209.x.x
Working on: N+, CCENT
Associates Degree: Lincoln Technical Institute ( DO NOT GO!)
Bachelors degree in progress: Computer Information Systems and Cyber security - Strayer University