Subnet Expert

CIDR /30 Subnet Reference

Detailed information about IPv4 /30 subnets

/30 Subnet Details

A /30 network has very few usable addresses and is typically used for point-to-point links or very small network segments.

Key Information

CIDR Notation/30
Subnet Mask255.255.255.252
Binary Subnet Mask11111111 11111111 11111111 11111100

Host Information

Total Addresses4
Usable Hosts (Standard)2
AWS Usable IPs2
Azure Usable IPs2
GCP Usable IPs0

Using /30 in Networks

A CIDR /30 subnet has 2 usable IP addresses for hosts. This is a relatively small subnet suitable for specific network segments.

Smaller subnets like this help improve network security and reduce broadcast domain size.

Cloud Provider Considerations

Cloud providers reserve some IP addresses in each subnet for internal use, resulting in fewer usable IPs:

  • AWS: 2 usable IPs(reserves 5 IPs per subnet)
  • Azure: 2 usable IPs(reserves 5 IPs per subnet)
  • GCP: 0 usable IPs(reserves 4 IPs per subnet)

When planning your cloud infrastructure, consider these reserved addresses to accurately size your subnets.

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