In IP addressing, what two components of an address does a subnet mask explicitly separate?

Introduction / Context:
Subnet masks are fundamental to IPv4 addressing. They determine which portion of an IP address identifies the network and which portion identifies the host within that network.

Given Data / Assumptions:

• We are working with IPv4 addressing.
• A subnet mask is applied via bitwise AND with an IP address.
• Outcome: network portion vs host portion.

Concept / Approach:
The mask has contiguous 1s for the network bits followed by 0s for host bits. ANDing the IP with the mask yields the network ID. The remaining low-order bits designate host IDs within that network.

Step-by-Step Solution:
Write IP in binary and align it with the mask.Mask 1s select the network bits; 0s select the host bits.Thus, the mask delineates network ID from host ID.

Verification / Alternative check:
Compute any sample: 192.168.1.75 AND 255.255.255.0 = 192.168.1.0 (network ID); host ID is .75 in that subnet.

Why Other Options Are Wrong:
DHCP scopes: An admin construct, not defined by masks.

Domains: DNS concept, unrelated to IP masks.

Subnets: Masks create subnets, but the separation is network vs host.

Routing metrics: Determined by protocols, not masks.

Common Pitfalls:
Confusing “subnet” with “network ID”; the mask carves the boundary, not the routing policy.

Final Answer:
Network ID and host ID