Which of the following is NOT a private IP address from the specified range?

The correct answer is that 192.169.1.1 is not a private IP address. To understand this, it's essential to look at the ranges designated for private IP addresses according to the Internet Engineering Task Force (IETF) standards. Private IP addresses fall within three specific ranges:

1. 10.0.0.0 to 10.255.255.255

2. 172.16.0.0 to 172.31.255.255

3. 192.168.0.0 to 192.168.255.255

The IP address 192.169.1.1 is outside of the private range defined for the 192.x.x.x block, as it falls within the public IP address space. Therefore, it cannot be assigned for private network use.

In contrast, the other options provided—10.0.20.90, 172.16.10.1, and 192.168.10.5—are all located within their respective private ranges and can be used within private networks. This distinction is vital for understanding how networking operates in both private and public contexts.