Phase 2 Master Exam Bank: IP Addressing & Subnetting Math

An IPv4 address is a 32-bit logical software address assigned to network interfaces to uniquely identify hosts on an IP network.

An IPv4 address contains exactly 32 bits divided into four 8-bit octets.

Dotted-decimal notation represents 32-bit binary IP addresses as four decimal numbers separated by dots (e.g. 192.168.1.1).

192.168.1.1

00001010.00000000.00000000.00000001

128, 64, 32, 16, 8, 4, 2, 1

A Subnet Mask is a 32-bit value of consecutive 1s followed by consecutive 0s that separates the Network ID from the Host ID.

Classless Inter-Domain Routing (CIDR) notation expresses the subnet mask as a slash followed by the count of network prefix 1-bits (/N).

255.255.255.0

255.255.255.192

255.255.255.224

255.255.255.240

255.255.255.252

The first address in a subnet (all host bits set to 0), representing the entire sub-network.

The last address in a subnet (all host bits set to 1), used to send traffic to all nodes in that subnet.

2^h - 2 (where h is the number of host bits).

We subtract 2 because the Network ID (all 0s) and Broadcast ID (all 1s) cannot be assigned to individual hosts.

Legacy IP scheme dividing the 32-bit address space into fixed-length classes (Class A, B, C, D, E).

Range: 1.0.0.0 to 127.255.255.255. Default Mask: 255.0.0.0 (/8).

Range: 128.0.0.0 to 191.255.255.255. Default Mask: 255.255.0.0 (/16).

Range: 192.0.0.0 to 223.255.255.255. Default Mask: 255.255.255.0 (/24).

Multicast group communication (Range: 224.0.0.0 to 239.255.255.255).

Experimental and research purposes (Range: 240.0.0.0 to 255.255.255.255).

Special non-routable IP ranges reserved for local private LAN networks to conserve IPv4 space.

10.0.0.0/8 (10.0.0.0 to 10.255.255.255)

172.16.0.0/12 (172.16.0.0 to 172.31.255.255)

192.168.0.0/16 (192.168.0.0 to 192.168.255.255)

Testing local TCP/IP software stack implementation on the host without sending traffic over physical wire.

Range 169.254.0.0/16 assigned automatically by Windows/OS when a DHCP server fails to respond.

A binary logic operation where 1 AND 1 = 1, and any other combination = 0, used by routers to extract Network ID.

Mask /26 = 255.255.255.192. 75 AND 192 = 64. Network IP = 192.168.10.64/26.

Block size S = 256 - 192 = 64. Next net = 128. Broadcast = 192.168.10.127.

First usable = 192.168.10.65. Last usable = 192.168.10.126.

Block Size S = 256 - Mask Octet Value.

S = 256 - 224 = 32.

S = 256 - 240 = 16.

S = 256 - 252 = 4.

Borrow 2 bits => CIDR /26 (Mask 255.255.255.192). Subnets: 192.168.1.0/26, 192.168.1.64/26, 192.168.1.128/26, 192.168.1.192/26.

Wildcard = 255.255.255.255 - 255.255.255.0 = 0.0.0.255.

Wildcard = 255.255.255.255 - 255.255.255.192 = 0.0.0.63.

Subnet A (Sales): 192.168.50.0/25 (Range .1-.126, Bcast .127) Subnet B (Eng): 192.168.50.128/26 (Range .129-.190, Bcast .191) Subnet C (HR): 192.168.50.192/27 (Range .193-.222, Bcast .223) Subnet D (IT): 192.168.50.224/28 (Range .225-.238, Bcast .239) Subnet E (WAN): 192.168.50.240/30 (Range .241-.242, Bcast .243)

Full derivation table partitioning 172.16.0.0/16 for Main (2000 hosts /21), North (900 hosts /22), South (400 hosts /23), East (120 hosts /25), and 3 WAN links (/30).

MAC 00:11:22:33:44:55 => Insert FF-FE => 0011:22FF:FE33:4455 => Flip 7th bit (00->02) => Interface ID = 0211:22ff:fe33:4455.

Summarize 192.168.0.0/24 through 192.168.3.0/24 into single prefix 192.168.0.0/22.

RIPv1 automatically summarizes classful boundaries causing black-hole routing; RIPv2 and OSPF support VLSM classless updates.

8 hextets of 16 bits each. Rule 1: Omit leading zeros. Rule 2: Compress single longest contiguous run of zeros with double colon ::.

Parsed into 48-bit Global Routing Prefix, 16-bit Subnet ID, and 64-bit Interface ID.

Automatically configured on every IPv6 interface using fe80::/10 prefix combined with EUI-64 or random Interface ID.

ff02::1 reaches all IPv6 nodes on link; ff02::2 reaches all IPv6 routers on link.

Combining multiple contiguous /24 prefixes into a single /20 routing table entry.

Worked solution for VLSM subnet allocation problem 11 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 12 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 13 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 14 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 15 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 16 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 17 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 18 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 19 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 20 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 21 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 22 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 23 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 24 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 25 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 26 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 27 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 28 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 29 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.

Worked solution for VLSM subnet allocation problem 30 providing binary bit mask calculations, network range boundaries, and wildcard mask derivations.