Proxy subnets: why addresses from one block are blocked together, and how many a plan spreads over

A subnet is a block of neighbouring addresses that share their first digits, such as the 256 addresses from 192.168.99.0 to 192.168.99.255, written 192.168.99.0/24. Sites and blocklists often judge a whole block at once, because a block usually has one owner, so many proxies from one subnet can be blocked together. A list of datacenter proxies spread over many subnets is harder to block in one go than the same number in one block, and some providers print how many subnets a package covers.

Answer · The live comparison uses prices checked up to Oct 24, 2026; every figure in the text keeps the date it was checked. Decodo shows its prices + VAT, so every Decodo figure on this page is before VAT.

What a subnet is

An IPv4 address is 32 bits, written as four numbers from 0 to 255. A subnet is written as an address, a slash and the number of leading bits every address in the block shares. The standard that defines the notation gives the example: the network 192.168.99.0 “is defined as the prefix 192.168.99.0/24; the most significant 24 bits are ones and the least significant 8 bits are zeros” (RFC 4632). The 8 bits left over make 256 addresses, which is why “a /24” is the usual unit for a block of proxies.

Blocks are handed out in that form. In the same standard’s words, the regional registries “allocate or assign smaller address blocks to Local Internet Registries (LIRs) or Internet Service Providers (ISPs)”, which may pass smaller blocks on to their customers (RFC 4632). A proxy provider’s datacenter addresses come in such blocks from its hosting companies.

Why sites block a whole subnet

Address lists record blocks, not only single addresses. MaxMind’s Anonymous IP database, which sites use to spot proxies, lists each entry as “the IPv4 or IPv6 network in CIDR format such as “2.21.92.0/29” or “2001:4b0::/64”” (MaxMind), and Spamhaus “lists /64 subnets of IPv6 addresses” (Spamhaus). A site that sees abuse from several addresses in one block can block the block. A hundred proxies in one /24 can then stop working together; spread over twelve subnets, they fail in smaller groups.

It does not work the other way round: addresses spread over many subnets still share their owner. A site that blocks every address a hosting company holds blocks them all, however many subnets they span (proxy IP reputation).

Many subnets or one private subnet

Datacenter proxies are sold both ways:

• Spread over several subnets, so one blocked block takes only part of the list with it. Some providers print the count per package, as the box at the top of this page shows.
• A private subnet of your own, a whole block that no other customer uses, so its record is yours alone. It costs a whole block at once.

Rotating residential and mobile proxies need neither: their addresses belong to many home and carrier networks, and change as you go (static vs rotating proxies).

How many subnets a rotating datacenter pool spreads over

A rotating datacenter plan gives you a gateway, not a list, so no package card counts its subnets. Proxyway, a proxy review site, measured them in its Proxy Market Research 2026: it sent US requests through each provider’s rotating datacenter pool, “70k connection requests over 7 days (10k/day)”, and counted the /24 subnets the addresses came from. It says “the majority of data were collected in March and April of 2026”. The nine providers we track, of the ten it tested:

The top three are a different kind of pool. In Proxyway’s words, “DataImpulse and Evomi continue to source datacenter proxy servers through an SDK, and apparently so does Infatica”, and “it’s immediately obvious which providers crowdsource their datacenter proxies”: an address gathered one machine at a time rarely shares its block with the next, while a provider that rents whole blocks fills each one. These are one test’s counts for US addresses at one time, not a promise of what your plan will give you.

How to see the subnets you were given

Two addresses are in the same /24 when their first three numbers match: 203.0.113.7 and 203.0.113.200 share one block; 203.0.113.7 and 198.51.100.7 do not. Sort your proxy list and count the distinct first-three-number groups; that count is the number of /24 subnets the list spans.

On Linux or macOS, with your list saved one proxy a line as proxies.txt (address first, as in 203.0.113.7:8080:user:pass), one command gives the count:

cut -d. -f1-3 proxies.txt | sort -u | wc -l

For the three example addresses above it prints 2. A list that gives host names instead of addresses needs them looked up first.