/21 Subnet Guide
Learn what a /21 IPv4 subnet means, including subnet mask, total addresses and usable hosts.
/21 CIDR Details
CIDR/21
Subnet Mask255.255.248.0
Total Addresses2,048
Usable Hosts2,046
Explanation: A /21 prefix uses 21 bits for the network and 11 bits for host addresses.
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This page is useful for subnet planning, CCNA study, MikroTik IP addressing, VLAN design and firewall documentation.