A new network is being created to support 126 users .

To support 126 users , the subnet must provide at least 126 usable host addresses . In IPv4 subnetting, usable hosts are calculated as: (2^(host bits)) − 2 , subtracting the network and broadcast addresses.

A /25 leaves 7 host bits (because 32 − 25 = 7). That yields 2^7 = 128 total addresses , and 128 − 2 = 126 usable —an exact fit and therefore the most efficient option listed.

A /24 provides 256 total addresses and 254 usable, which would waste more addresses than necessary. A /23 provides 512 total addresses and 510 usable—far more waste. A /26 leaves 6 host bits, giving 64 total addresses and 62 usable, which is not enough for 126 users.

The 10.2.2.0 address is within the private 10.0.0.0/8 range, so it’s appropriate for internal addressing. Therefore, 10.2.2.0/25 is the correct CIDR range for efficiently supporting 126 hosts.