IPRangeExplorer

121.0.0.0/9

Public

Class A — /9 prefix — 8,388,606 usable hosts

Network Address
121.0.0.0
Broadcast Address
121.127.255.255
Subnet Mask
255.128.0.0
Usable Hosts
8,388,606
First Usable IP
121.0.0.1
Last Usable IP
121.127.255.254
Total IPs
8,388,608
Prefix Length
/9

Network address — the base address of the block (121.0.0.0). All devices in this subnet share this prefix. Cannot be assigned to a host.

Broadcast address — packets sent to 121.127.255.255 are delivered to every device in the subnet. Also reserved — not assignable.

Usable hosts — the 8,388,606 addresses between those two that you can assign to servers, VMs, or interfaces.

Subnet mask — 255.128.0.0 is the dotted-decimal equivalent of /9. Older tools and Cisco configs use this format instead of CIDR slash notation.

Full Details

CIDR Notation 121.0.0.0/9
Network Address 121.0.0.0
Broadcast Address 121.127.255.255
Subnet Mask 255.128.0.0
Wildcard Mask 0.127.255.255
Prefix Length /9
IP Address Class Class A
Total IP Addresses 8,388,608
Usable Host Addresses 8,388,606
First Usable IP 121.0.0.1
Last Usable IP 121.127.255.254
Network (Hex) 0x79000000
Broadcast (Hex) 0x797FFFFF
Address Type Public / Globally Routable

Binary Representation

Network Address
01111001 01111001.00000000.00000000.00000000
Subnet Mask
11111111.10000000.00000000.00000000

The first 9 bits (1s in the mask) identify the network. The remaining 23 bits identify hosts within the network.

Split into Equal Subnets

Split 121.0.0.0/9 into 2 equal /10 subnets (4,194,302 usable hosts each).

# CIDR Network First Usable Last Usable Broadcast Hosts
1 121.0.0.0/10 121.0.0.0 121.0.0.1 121.63.255.254 121.63.255.255 4,194,302
2 121.64.0.0/10 121.64.0.0 121.64.0.1 121.127.255.254 121.127.255.255 4,194,302

/9 Subnet Reference

Total IPs 8,388,608
Usable Hosts 8,388,606
Subnet Mask 255.128.0.0
Wildcard 0.127.255.255
Full /9 reference →

Related Ranges

Parent /8 block 121.0.0.0/8 Sibling /9 block 121.128.0.0/9

Adjacent Prefix Sizes

/7 33,554,430 hosts /8 16,777,214 hosts /9 8,388,606 hosts /10 4,194,302 hosts /11 2,097,150 hosts

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