Why NAC Projects Stall: The Hidden Technical Complexities and NAC Alternatives Reshaping Network Security

Network Access Control (NAC) remains one of the most paradoxical technologies in enterprise security. NAC adoption has been in steady decline. According to Forrester's Business Technographics® surveys, implementation of NAC solutions dropped from 59% of security decision-makers in 2018 to just 44% by 2022—a 25% decline in four years. Even more telling, Forrester found that "most of the implementations seem to favor Wi-Fi connectivity, while many wired ports remain unprotected," highlighting the limited scope of successful NAC deployments from vendors like Fortinet FortiNAC, Forescout, Cisco Identity Services Engine (ISE), Aruba ClearPass, and others (Source). The reason? It's not that security teams don't understand the value—it's that NAC's inherent technical complexities create implementation challenges that even the most skilled teams struggle to overcome.

If your NAC project has stalled, you're not alone. And more importantly, it's not your fault. The technology itself presents fundamental architectural challenges that make successful deployment exceptionally difficult. Let's explore the technical realities behind NAC's struggles and how modern alternatives like Zero Trust Network Access (ZTNA) and microsegmentation are providing the security outcomes organizations originally sought from NAC.

The 802.1X Authentication Challenge: Where Theory Meets Reality

At the heart of most NAC deployments lies 802.1X, the IEEE standard for port-based network access control. In theory, 802.1X provides robust authentication through the Extensible Authentication Protocol (EAP). In practice, it creates a web of technical dependencies that can bring deployments to their knees.

Certificate Management Complexity

EAP-TLS, considered the gold standard for 802.1X security, requires a complete Public Key Infrastructure (PKI) deployment. This means:

• Deploying certificate authorities (CAs) and maintaining root certificate trust chains
• Distributing unique certificates to thousands of endpoints
• Managing certificate lifecycle events, including renewal and revocation
• Ensuring all devices trust the RADIUS server's certificate

As one network administrator described in the Aruba Airheads Community: "An erroneous update was deployed to our PCs, resulting in a widespread failure of 802.1X authentication for both wired and wireless connections. The root of the problem was that the PCs ceased to recognize the RADIUS certificate on Clearpass, likely because they lost trust in the root CA." This catch-22 scenario—where devices need network access to download the certificate fix but can't authenticate without the certificate—exemplifies why NAC deployments are so fragile in real-world enterprise environments.

The Authentication Failure Cascade

Technical teams often discover that authentication failures can outnumber successes. One ClearPass deployment serving 400,000+ endpoints experienced 5.85 million failed authentication attempts out of 9.58 million total attempts in just 24 hours. The culprits included:

• Switches sending RADIUS requests for MAC authentication every minute for unknown devices
• Docking stations attempting authentication when laptops enter sleep mode
• IP phones falling back to MAC authentication due to certificate issues
• Devices with incorrect 802.1X profiles retrying authentication every 60 seconds

These aren't configuration errors—they're inherent behaviors in how 802.1X interacts with modern enterprise environments.

The BYOD and IoT Device Dilemma

Perhaps no challenge better illustrates NAC's limitations than the explosion of unmanaged devices in modern networks. The fundamental issue is that NAC was designed for a world of managed corporate endpoints, not today's heterogeneous device landscape.

Why IoT Devices Break NAC

Internet of Things (IoT) devices—from medical equipment to manufacturing sensors—typically:

• Lack computational resources to run NAC supplicants or agents
• Don't support 802.1X protocols due to limited operating systems
• Have no user interface for credential entry or certificate enrollment
• Cannot be "remediated" with security patches or configuration changes
• Use proprietary protocols incompatible with standard authentication methods

The result? Organizations default to MAC Authentication Bypass (MAB), which relies on easily spoofed MAC addresses and provides no real authentication. As research from Ordr notes, NAC "is effective in managing security risks only for known devices, and devices that are associated with human users." By the time security teams address unmanaged devices, "the best-case scenario is a NAC solution where most unmanaged devices are simply whitelisted and ignored."

The 33% Coverage Reality

Here's a sobering statistic: due to these technical limitations, NAC solutions can effectively secure only about 33% of devices on modern networks. The remaining 67%—IoT sensors, medical devices, building automation systems, industrial controllers—remain outside NAC's protective reach, creating massive security blind spots that attackers can exploit for lateral movement.

Operational Overhead: The "Don't Touch It" Syndrome

Even when NAC deployments technically function, they often become operational nightmares that IT teams fear to modify. This isn't a skills issue—it's a complexity issue inherent to the technology.

Resource Requirements at Scale

A comprehensive NAC deployment typically requires:

• A dozen or more full-time employees across Security Operations, Network Engineering, and platform management
• 3-12 months for initial deployment planning and configuration
• Up to 6 years for global implementation across multiple sites
• 24/7 on-call support for authentication failures and policy exceptions
• Continuous VLAN management as traditional NAC relies on VLAN proliferation for segmentation

The Vendor Lock-In Trap

NAC solutions are typically optimized for specific vendor ecosystems. Cisco ISE works best with Cisco infrastructure, Aruba ClearPass with HPE equipment, and Forescout with its specific plugin architecture. In heterogeneous environments—which describes most modern enterprises—this creates integration nightmares. As Portnox research indicates, "modern networks are rarely homogenous, leading to additional complexity in integrating diverse systems."

Why Traditional NAC Struggles with Modern Architecture

The fundamental challenge is that NAC was designed for a different era of networking—one with clear perimeters, managed devices, and on-premises infrastructure.

The VLAN Sprawl Problem

Traditional NAC architectures require separate VLANs for:

• Compliant devices
• Non-compliant devices
• Quarantine networks
• Guest networks
• Various privilege levels and department segments

This VLAN proliferation becomes unmanageable at scale, with some organizations maintaining hundreds or thousands of VLANs. Each VLAN requires careful configuration, routing rules, and access control lists (ACLs), creating a fragile house of cards that can collapse with a single misconfiguration.

Branch Office Deployment Challenges

While some organizations achieve NAC success at headquarters, branch office deployments consistently fail due to:

• Infrastructure dependencies requiring local RADIUS servers or reliable WAN connectivity
• Hardware requirements for dedicated NAC appliances at each location
• The fail-open dilemma: If NAC servers become unreachable, do you allow all traffic (security failure) or block all traffic (business continuity failure)?
• Support limitations with no on-site IT staff to troubleshoot authentication issues

Industry-Specific NAC Challenges

Different industries face unique NAC implementation hurdles that compound the general technical challenges:

Healthcare: The Medical Device Nightmare

Hospitals operate thousands of IoT-enabled medical devices—MRI machines, infusion pumps, ventilators, patient monitors—that cannot comply with traditional NAC policies. These devices often run legacy operating systems, cannot be patched due to FDA regulations, and lack the ability to perform 802.1X authentication. The result? Healthcare organizations must maintain massive MAC address whitelists or place all medical devices on less-secure network segments, creating exactly the lateral movement risks NAC was meant to prevent.

Manufacturing: Production vs. Security

Manufacturing facilities face a cruel choice: implement NAC and risk production disruptions, or maintain security gaps. Programmable Logic Controllers (PLCs), industrial sensors, and legacy automation systems often run for decades without updates. Industry data shows high-speed production lines can process 4,000+ units per minute, meaning any authentication failure that halts production translates to thousands of dollars in losses per minute. This is why, as one NAC vendor acknowledges, organizations harbor "fears of service disruption with wired deployments" in manufacturing—NAC is an "all-or-nothing solution" that cannot support the incremental, low-risk approaches manufacturers require.

Financial Services: The Branch Office Problem

Financial institutions achieve their best NAC deployments in wireless environments where authentication is expected and technically straightforward. However, they still struggle significantly with wired network implementations where legacy systems, trading terminals, and fixed infrastructure resist 802.1X authentication. Branch locations compound these challenges—each branch requires local NAC infrastructure or reliable WAN connectivity back to central authentication servers. When connections fail—and they do—branches face the impossible choice between security (blocking all access) and business continuity (allowing unauthenticated access).

The Evolution: ZTNA and Microsegmentation as Modern Alternatives

The good news is that modern alternatives address NAC's fundamental limitations while delivering the security outcomes organizations need.

Zero Trust Network Access (ZTNA)

ZTNA represents a fundamental shift from network-centric to identity-centric security. According to recent cybersecurity research, 79% of organizations have either already adopted ZTNA or plan to do so within the next 24 months. The key advantages include:

• No network changes required - ZTNA overlays existing infrastructure
• Cloud-native architecture - Built for hybrid and remote work environments
• Continuous verification - Not just at connection time, but throughout the session
• Application-level access - Users get access to specific applications, not network segments
• Direct-to-app connectivity - Eliminates VPN bottlenecks and improves performance

Identity-Based Microsegmentation

Modern microsegmentation platforms take a different approach entirely:

• Agentless deployment that works with all device types, including IoT/OT
• Identity-driven policies that follow devices regardless of network location
• Software-defined enforcement without VLAN or ACL dependencies
• Rapid deployment starting in weeks with full policy coverage achieved in 1-3 months for most organizations (up to 2 years for 500+ location enterprises)
• 99% device auto-classification without manual intervention

As NIST's Zero Trust Architecture guidance (SP 800-207) emphasizes, the focus shifts from network location to "users, assets, and resources"—exactly what microsegmentation delivers.

A Pragmatic Path Forward: NAC Plus Modern Solutions

Here's an important point: NAC isn't inherently bad technology. For specific use cases—particularly wireless authentication and compliance requirements—it can still provide value. The key is understanding its limitations and complementing it with modern solutions.

Where NAC Still Works

NAC shows the highest success rates in:

• Wireless-only deployments where users expect authentication
• Greenfield installations with homogeneous infrastructure
• Limited-scope pilots in single buildings or departments
• Compliance requirements that specifically mandate 802.1X

The Complementary Approach

Many successful organizations now use a hybrid strategy:

• Keep NAC for basic network admission where it works well (wireless, managed devices)
• Deploy microsegmentation for lateral movement prevention across all devices
• Implement ZTNA for remote and cloud access to replace VPN complexity
• Use identity-based policies that work across all three technologies

This approach provides comprehensive security without requiring a complete NAC deployment across every network port and device type.

Real-World Success: The Hybrid Model

Main Line Health's security team publicly described their journey from NAC to microsegmentation. Their prior NAC efforts were "slow, complex, and resource-intensive," requiring "a team of specialists" and multi-year rollouts. By keeping NAC for basic wireless authentication while deploying identity-based microsegmentation for lateral movement prevention, they achieved:

• Comprehensive device discovery and automated classification
• Real-time, risk-based enforcement
• Compliance alignment with Zero Trust principles

All without disrupting patient care or requiring network redesigns.

Making the Business Case for Modern Alternatives

When evaluating NAC alternatives, consider these compelling metrics:

Cost Comparison

• NAC - Requires a dozen staff, 3-12 months initial deployment, up to 6 years for global rollout
• Modern Microsegmentation - Starts at 1 or 2 FTEs and deploys in a few weeks with full policy coverage achieved from a month to several months. Very large organizations with 500+ locations can be fully implemented in about two years

Risk Reduction

• NAC - Covers only 33% of devices, leaving 67% vulnerable to lateral movement
• Modern Solutions - Cover 100% of devices, including IoT/OT, without agents

Operational Impact

• NAC - Requires change control windows, network downtime, constant troubleshooting
• Modern Solutions - Deploy over existing infrastructure with zero downtime

Key Takeaways for Security Leaders

If you're evaluating NAC alternatives or struggling with a stalled NAC project, consider these realities:

• NAC's complexity is inherent to its architecture, not a reflection of your team's capabilities
• The 33% device coverage limitation is a technical reality, not a deployment failure
• Modern alternatives exist that deliver NAC's intended outcomes without its complexity
• Hybrid approaches work: You can keep NAC where it provides value while deploying modern solutions for comprehensive security
• The market is moving: With 79% of organizations adopting ZTNA, the shift is already underway

Conclusion: The Future of Network Access Security

The networking industry is experiencing a fundamental shift. While NAC served an important role in network security's evolution, modern threats and architectures demand modern solutions. ZTNA and microsegmentation represent not just alternatives to NAC, but an evolution in how we think about access control and network security.

For organizations still wrestling with NAC deployments, remember: the struggles you're experiencing are shared across the industry. According to Security Uncorked's analysis, NAC installations "require three experts, two special moon phases, and a sacrifice to the networking gods"—a humorous but painfully accurate description of the technology's complexity.

The path forward isn't about declaring NAC a failure, but about recognizing its limitations and embracing complementary or alternative approaches that deliver the security outcomes your organization needs. Whether that's ZTNA for remote access, microsegmentation for lateral movement prevention, or a hybrid approach that leverages the best of all technologies, the key is choosing solutions that align with your current infrastructure, device landscape, and security objectives.

As we move into 2026 and beyond, the question isn't whether to evolve beyond traditional NAC—it's how quickly organizations can adopt modern alternatives to address today's security challenges while preparing for tomorrow's threats. The good news? You don't have to abandon your NAC investment entirely. By understanding where NAC provides value and where modern solutions excel, you can build a security architecture that truly protects your organization without the complexity that has plagued NAC deployments for two decades.

For security architects and CISOs researching NAC alternatives, modern NAC solutions, or network access control alternatives, the key is understanding that technology evolution, not vendor selection, drives successful security outcomes. The future belongs to identity-based, zero-trust architectures that protect every device, user, and application—regardless of location or network topology. If you want to learn more about how Elisity works, schedule a conversation with us.