/24 subnet diversity in proxy lists, explained

What is a /24 subnet?

A /24 is a block of 256 consecutive IPv4 addresses that share their first 24 bits, which means their first three numbers. 203.0.113.24 and 203.0.113.97 are in the same /24, 203.0.113.0/24. 198.51.100.7 is in a different one.

The number after the slash is the prefix length from CIDR notation (RFC 4632): it counts the fixed bits. A /24 fixes 24 of 32 bits, leaving 8 bits, so 2^8 = 256 addresses. A /23 holds 512, a /22 holds 1,024, and so on. In global BGP routing, most networks do not accept IPv4 announcements smaller than a /24, so a /24 is the smallest block that can be routed on its own across the internet.

Why do some websites rate-limit per subnet?

Some websites count requests per /24 because neighboring addresses usually belong to the same operator and often to the same customer. If one address in a block misbehaves, a cautious site may slow down or challenge the whole block rather than chase each address.

For you, this has two effects:

• Shared fate. Ten IPs in one /24 can share one reputation or one limit on such sites. A problem caused by a previous user of a neighboring address can reach yours.
• No extra capacity. If a site applies its limit per subnet, more IPs in the same /24 add nothing for that site. This is a reason to respect the limit, not to work around it: the sizing guide explains why a site's pace applies to your whole job.

Many websites do not look at subnets at all. Subnet diversity matters most for redundancy: spreading IPs over several blocks means one blocked block does not stop every job.

Do RackProxies orders include several /24 subnets?

They can, but we do not promise a number. An order of several IPs can include addresses from more than one /24 subnet, but no minimum number of subnets is promised. Your IPs come from upstream hosting partners, and the mix of blocks depends on what is online in the country and city you pick.

If your job needs IPs in more than one /24, say so to support before or after you buy; we will tell you what the current stock allows. Replacements follow the usual rule. If an IP does not work or is unusable for a lawful use, write to support: we fix it or replace it with an IP in the same country, subject to stock. Orders in several countries or cities are spread across different networks by nature, because each location has its own blocks.

How do I check the subnets in my proxy list?

Group the IPs by their /24 and count each group. Download your list as TXT from your account (one IP:PORT:USERNAME:PASSWORD line per IP; see the connection format) and run the script below with Python 3. It uses only the standard library.

"""Group a proxy list by /24 subnet. Input: one IP:PORT:USERNAME:PASSWORD per line."""
import ipaddress
import sys
from collections import Counter

path = sys.argv[1] if len(sys.argv) > 1 else 'proxies.txt'
subnets = Counter()
with open(path, encoding='utf-8') as handle:
    for line in handle:
        line = line.strip()
        if not line:
            continue
        ip = line.split(':')[0]
        network = ipaddress.ip_network(ip + '/24', strict=False)
        subnets[str(network)] += 1

total = sum(subnets.values())
print(total, 'IPs in', len(subnets), 'distinct /24 subnets')
for network, count in subnets.most_common():
    print(f'{network:<18} {count:>4} IPs  ({count / total:.0%})')

6 IPs in 3 distinct /24 subnets
203.0.113.0/24        3 IPs  (50%)
198.51.100.0/24       2 IPs  (33%)
192.0.2.0/24          1 IPs  (17%)