CIDR /4Private (RFC 1918)
/4 Subnet Mask (240.0.0.0) - Usable Hosts & CIDR | ipcalc.net
Everything about /4 subnets: Subnet mask 240.0.0.0, wildcard mask 15.255.255.255, 26,84,35,454 usable hosts, binary breakdown, and Cisco configuration templates.
Enter any notation: 192.168.1.1/24, 10.0.0.1 255.255.255.0, or plain IP
Subnet Mask Prefix: /4Netmask: 240.0.0.0
Presets:
32-Bit Subnet Boundary Visualizer
Click any bit position to adjust the CIDR prefix boundary
Network (4 bits)
Host (28 bits)
Octet 110Mask: 240
11110000
Octet 20Mask: 0
00000000
Octet 30Mask: 0
00000000
Octet 40Mask: 0
00000000
Usable Hosts
268,435,454
Total IPs: 268,435,456
Network Address
0.0.0.0
Prefix: /4
Usable Host Range
0.0.0.1
15.255.255.254
Broadcast Address
15.255.255.255
Subnet Broadcast
Detailed Subnet Breakdown
Private (RFC 1918)Subnet Mask
240.0.0.0
Wildcard Mask (Cisco ACL)
15.255.255.255
Hexadecimal IP / Mask
0x0A000000 / 0xF0000000
Integer / Decimal IP
167772160
IP Class & Routing
Class A • Classless Inter-Domain Routing (CIDR)
Reverse DNS (in-addr.arpa)
0.0.0.10.in-addr.arpa
Cisco IOS Command Templates
ip address 10.0.0.0 240.0.0.0
access-list 1 permit 0.0.0.0 15.255.255.255
Technical Subnet Specifications
Prefix Length/4
Dotted Decimal Subnet Mask240.0.0.0
Wildcard Mask (Inverse)15.255.255.255
Total Available IP Addresses26,84,35,456
Usable Host Capacity26,84,35,454 hosts
Network Bits vs Host Bits4 Network / 28 Host
Binary Subnet Mask11110000.00000000.00000000.00000000
Cisco IOS Configuration
Copy-paste templates for Cisco router and switch interface setup:
! Configure Interface
interface GigabitEthernet0/0/1
ip address 0.0.0.1 240.0.0.0
no shutdown
! Access-Control List
access-list 10 permit 0.0.0.0 15.255.255.255
Tip: Wildcard mask is computed by inverting the subnet mask (
~mask).Typical Network Use Cases for /4
A /4 network block provides 26,84,35,456 total IP addresses with 26,84,35,454 usable host interfaces.
Designated Role: Subnet block.
Frequently Asked Questions: /4 (240.0.0.0)
Authoritative answers to common /4 subnetting, host capacity, and networking questions.
Q1How many usable hosts are in a /4 subnet?
A /4 subnet provides 26,84,35,454 usable host IP addresses out of 26,84,35,456 total addresses. In IPv4 networking, 2 addresses are reserved: the network address (0.0.0.0) and the directed broadcast address (15.255.255.255). Formula: 2^(32 - 4) - 2 = 26,84,35,454 usable hosts.
Q2What is the subnet mask and wildcard mask for /4?
The dotted-decimal subnet mask for a /4 prefix is 240.0.0.0. The corresponding wildcard mask (used in Cisco ACLs and OSPF network statements) is 15.255.255.255. In binary, the subnet mask consists of 4 network bits (1s) followed by 28 host bits (0s).
Q3What are the network, broadcast, and usable IP ranges for 10.0.0.0/4?
For the 10.0.0.0/4 subnet: the Network Address is 0.0.0.0, the Broadcast Address is 15.255.255.255, and the usable host range extends from 0.0.0.1 through 15.255.255.254. Any host interface configured in this subnet must have an IP within this range and netmask 240.0.0.0.
Q4What is a /4 subnet typically used for in network design?
A /4 subnet is typically deployed for subnet block. In enterprise and cloud environments (such as AWS VPCs or Azure VNets), /4 allocations provide the optimal balance between host capacity and address conservation.
Q5What does /4 mean in CIDR notation?
Classless Inter-Domain Routing (CIDR) notation expresses the subnet mask as a forward slash followed by the prefix length. A /4 prefix indicates that the first 4 bits of the 32-bit IPv4 address are locked for network identification, leaving the remaining 28 bits available for addressing host interfaces.