Subnet Address Role Sorter

About this interactive

With a classful mask, network and broadcast addresses are easy to spot: the host octets are all 0 or all 255. A custom mask moves the line, so the test has to move with it. A network address has every host bit 0 and a broadcast address every host bit 1, where the host bits are the ones the prefix leaves, not the ones the class leaves. The quick way is to find the block. 212.40.3.112/28 leaves 4 host bits, so the blocks are 16 wide in the last octet: 80-95, 96-111, 112-127. 112 starts a block, so it is a network address; 95 ends one, so 212.40.3.95/28 is a broadcast address; 212.40.3.100/28 is in the middle, so it is a host. When the boundary is in the third or second octet, the block spans whole octets, and that is where .0 and .255 mislead: in 172.24.72.0/19 the block runs from 172.24.64.0 to 172.24.95.255, so 172.24.72.0 is a host, and 10.9.255.255/14 sits inside the block 10.8.0.0 to 10.11.255.255, so it is a host too. Nine of the twenty-four cards are drawn each run. After you check, every card shows its block and why it belongs where it does.

What you'll learn

Identify whether an IPv4 address with a custom prefix is the network address, the broadcast address or a usable host address of its subnet
Find the subnet range an address falls in from its prefix length, with the boundary in any octet

Aligned to

CompTIA Network+

1.7 Given a scenario, use appropriate IPv4 network addressing.

Cisco CCNA

1.6 Configure and verify IPv4 addressing and subnetting

Cisco CCST Networking

2.2 Identify IPv4 addresses and subnet formats

Key terms

Network Address: The first address in an IP network range that identifies the network itself and cannot be assigned to a host. It is formed when all host bits are set to zero.
Broadcast Address: The last address in an IP subnet range, formed when all host bits are set to one, used to send a single packet to every device on that network simultaneously.
Host Address: An IP address assigned to a specific device on a network; the host portion is neither all zeros nor all ones.
Classless Inter-Domain Routing: A method for allocating IP addresses and expressing routing prefixes that replaces the older classful addressing scheme by using variable-length prefix notation (e.g., /24). CIDR enables more efficient use of IPv4 address space and reduces the size of internet routing tables through route aggregation.
Bit Borrowing: The practice of taking bits from the host portion of a classful default subnet mask to create additional network subdivisions, extending the prefix length.

Topics

Address Types Network Address Broadcast Address Subnetting Interactive Categorize

About TechKnowSurge

TechKnowSurge builds IT and cybersecurity professionals through hands-on, concept-first training built around real understanding — not memorization. Free interactive tools, structured programs, and 25+ years of real-world experience, all in one place.

Explore free tools and programs →