/29 vs /28 vs /27 IP Blocks Explained for Dedicated Servers

Dedicated servers often require more than a single public IP address. Many hosting environments rely on multiple addresses for websites, mail servers, SSL domains, and network separation. This need introduces CIDR blocks such as the /29 subnet, /28 subnet, and /27 subnet. Each block size determines how many IP addresses a server can use. The total number of addresses does not equal the number available for services. 

Network and broadcast reservations decrease the pool of usable addresses in each subnet. This fact makes many administrators seek such questions as the number of usable IPs in /29, usable IPs in /28, or usable IPs in /27. This is a technical description of the /29 vs /28 vs /27. Practical hosting situations are also defined in the article to enable server owners to determine the size of an IP block to fit their infrastructure.

Key Takeaways from the Article

• A /29 subnet provides 8 total IP addresses, with 6 usable IPs in /29 after network and broadcast reservations.

• A /28 subnet offers 16 total addresses and 14 usable IPs in /28, suitable for multi-service server setups.

• A /27 subnet includes 32 total addresses with 30 usable IPs in /27, ideal for larger deployments and reseller hosting.

• The /29 vs /28 vs /27 comparison mainly depends on how many public services require dedicated IP addresses.

• Selecting the correct IP block size helps prevent IP shortages and supports the stable growth of dedicated server infrastructure.

What Are /27, /28, and /29 Subnets?

An IP subnet is a subdivision of a large address space into smaller address spaces. This segmentation is represented in the CIDR notation as a suffix /29, /28, or /27. The figure on the other side of the slash is the number of bits that determine the network part of the address. This notation determines how many addresses remain available for hosts inside the subnet.

Every subnet contains two reserved addresses:

• The network address identifies the subnet itself

• A broadcast address allows communication with all hosts inside the subnet

These reservations explain why the total address count differs from the usable count. A CIDR block /29 includes eight addresses, yet only six remain available for services. The same rule applies to the usable IPs in /28 and the usable IPs in /27. CIDR notation simplifies subnet organization without requiring complex calculations.

/29 vs /28 vs /27

Understanding the difference between these subnet sizes becomes easier with a direct IP block size comparison. The table below summarizes the total number of addresses and the usable IP counts.

The above comparison shows why administrators frequently evaluate /29 vs /28 when selecting address blocks for a server. Each increase in subnet size doubles the total address pool. Many readers also ask what a /29 IP block is when they begin deploying dedicated infrastructure. A /29 subnet remains the smallest commonly offered block in hosting environments. 

The usable IPs in /29 total six addresses, which support small service deployments. A /28 subnet increases flexibility with fourteen assignable addresses. The usable IPs in /27 expand the pool further and support large-scale hosting setups. Administrators who want a clearer understanding of subnet calculations and address ranges can review this guide on IP address calculation.

Which IP Block Size Fits Your Dedicated Server?

/29 Subnet: Small-Scale Hosting

A /29 subnet contains eight total addresses and six usable ones. The usable IPs in /29 suit environments with limited public services. Typical examples include:

• Small website hosting environments

• A few SSL-secured domains that require separate IP addresses

• A basic failover setup between two servers

• Simple mail and web server deployments

The configuration works well for early-stage applications or small business infrastructure. Many administrators select a CIDR block /29 when only a handful of services require public exposure. The /29 vs /28 comparison becomes relevant as infrastructure expands. A small subnet may reach capacity quickly if additional services require dedicated IP addresses.

/28 Subnet: Multi-Service Environments

A /28 subnet expands the address pool to sixteen total addresses. Fourteen of these remain usable for applications and services. The usable IPs in /28 allow more structured infrastructure. Organizations often allocate separate addresses to different service layers for stability and security.

Common scenarios include:

• Web servers, mail servers, and backup services on unique addresses

• Application environments with staging and production systems

• Monitoring and analytics services that require separate endpoints

• Multiple SSL domains with dedicated IP assignments

The /29 vs /28 decision frequently appears when businesses plan moderate growth. A /28 subnet provides a balanced allocation that supports expansion without excessive address cost. The usable IPs in /28 often suit mid-scale hosting platforms that run multiple public services.

/27 Subnet: Large Deployments and Resellers

A /27 subnet offers thirty-two total addresses and 30 usable IPs in /27. This allocation supports larger infrastructure deployments. Hosting providers, SaaS platforms, and reseller environments often require multiple IP addresses to separate services. The usable IPs in /27 allow greater architectural flexibility.

Typical use cases include:

• Reseller hosting platforms with multiple client websites

• Large application clusters across several nodes

• Multiple public services such as web, mail, APIs, and gateways

• Load balancers that distribute traffic across backend servers

The /27 subnet also supports infrastructure designs that isolate services across individual IP addresses. This approach improves security policies and simplifies routing management. Organizations that expect consistent growth often prefer this block size early in the deployment process.

IPv4 Scarcity and Cost Considerations

IPv4 address space remains limited worldwide. Most regional internet registries have exhausted their available pools, which forces providers to obtain addresses through transfers or leasing agreements. This shortage explains why hosting companies charge additional fees for larger IP allocations. A /27 subnet consumes more address resources than a CIDR block /29, which increases its cost.

Address planning, therefore, becomes an important step before deploying infrastructure. A clear strategy prevents the need for frequent subnet changes. Administrators who manage virtual or dedicated environments can benefit from the structured planning methods explained. Proper planning helps ensure the selected subnet supports both current workloads and future expansion. A structured approach to address allocation is explained in this guide on IP address planning for VPS environments.

Common Mistakes When Choosing an IP Block

Confusing Total IPs with Usable IPs

Many users assume that every address in a subnet remains assignable. This assumption leads to incorrect planning. A /29 CIDR block contains 8 addresses, but only 6 usable IPs remain after reservations. The same rule applies to usable IPs in /28 and usable IPs in /27. Understanding the difference between total and usable addresses prevents allocation errors.

Ordering a Block That Is Too Small

Small subnets often appear cost-effective at first. However, limited address capacity may restrict service expansion. A /29 subnet can become insufficient when multiple applications require dedicated IPs. Upgrading the subnet later may involve network adjustments.

Not Planning for Future Growth

Infrastructure requirements rarely remain static. New applications, services, or nodes often require additional addresses. Choosing a slightly larger block, such as a /28 subnet, may prevent future limitations. The /29 vs /28 decision should therefore take expected growth into account.

Ignoring Reverse DNS Requirements

Many services rely on reverse DNS records for security verification and email delivery. Each public IP often requires its own PTR record. Without an organized IP allocation process, reverse DNS management becomes complex. Clear address management simplifies DNS configuration and improves network reliability.

The Bottom Line

Understanding the /29 vs /28 vs /27 comparison helps server owners select the correct IP allocation for their infrastructure. A /29 subnet provides six usable addresses and is suitable for small hosting environments. A /28 subnet offers fourteen usable addresses and supports multi-service deployments. 

A /27 subnet provides 30 usable addresses and is suitable for large infrastructure or reseller hosting. The key factor involves matching subnet capacity with the number of services that require public IP addresses. Careful planning prevents address shortages and supports stable infrastructure growth. HostSailor offers dedicated servers with scalable IP allocation across all three block sizes, making it straightforward to select the right subnet from the start.

 

Frequently Asked Questions About /29 vs /28 vs /27 IP Blocks

What is the difference between /29 and /28 subnets?

A /29 subnet contains eight total addresses with 6 usable IPs in /29. A /28 subnet contains sixteen addresses with 14 usable IPs in /28. The /29 vs /28 comparison, therefore, shows more than double the usable capacity in a /28 subnet.

What is a /27 IP block used for?

A /27 subnet supports environments that require many public IP addresses. The usable IPs in /27 total thirty addresses. Reseller hosting platforms, clustered applications, and load-balanced services commonly rely on this allocation.

Why are only 6 IPs usable in a /29?

A CIDR block /29 includes eight addresses in total. Two addresses remain reserved for the network identifier and broadcast communication. This reservation leaves 6 usable IPs in /29 available for servers or services.

Which CIDR block should I choose for a dedicated server?

The correct choice depends on the number of services that require unique public IP addresses. A /29 subnet suits small hosting setups. A /28 subnet supports multi-service infrastructure. A /27 subnet works best for larger deployments that require many public endpoints.