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Zero Trust Network Access (ZTNA): A Comprehensive Guide


Remote workers, personal devices, public Internet, centralized networking, old VPNs, and outdated security – together they create a welcoming environment for an expensive security incident.

It’s important to get security in this environment right:

  1. The average cost of a data breach in 2023 reached $4.45 million, representing a 15% increase over the past three years. 
  2. Experts expect ransomware attacks cost businesses worldwide over $20 billion in 2023. These devastating attacks exploit weaknesses in corporate network security configurations.
  3. Fully 74% of data breaches involved human element errors, such as misuse of privileges and credentials

Zero Trust Network Access (ZTNA)’s practice of least privilege and continuous verification can significantly reduce these risks.

As organizations transition to remote work and cloud-based environments, traditional security measures are proving insufficient.

What is ZTNA?

Zero Trust Network Access (ZTNA) is a security model that operates on the principle of “never trust, always verify.” Traditional network security grants access based on a user’s location within the network perimeter. Once you’re in, you’re trusted to access everything.

ZTNA, however, continuously verifies every user and device attempting to access anything on your network. It does this regardless of their location, the device they’re using, or the applications and services they’re trying to access.

As a user, with ZTNA you’re never inherently trusted.

ZTNA solutions grant access to applications and data only after rigorous identification, authentication, and authorization processes. This approach minimizes the risk of unauthorized access within the network, offering a robust defense against cyber threats.

But… doesn’t continuous verification create delay?

You’d think so, but ZTNA’s model ensures that it doesn’t.

One of the standout features of ZTNA is its ability to continuously verify user and device authenticity without introducing latency or delays that could hinder productivity. How? By using several advanced techniques and technologies:

Contextual Awareness

ZTNA systems leverage contextual information such as user location, device type, and usage patterns to assess the credibility of authentication attempts. By understanding context, ZTNA quickly verifies identity, initiating exhaustive checks only when it sees anomalies.

Incremental Validation

ZTNA doesn’t revalidate every aspect of a user’s credentials during every access attempt. Instead, ZTNA verifies changes or abnormalities since the last session, ensuring speedy re-authentication.

Machine learning and AI

Advanced ZTNA solutions incorporate ML/AI to continuously analyze traffic patterns and user behavior. These technologies can identify and preempt potential security threats. This ensures that only necessary checks are performed, thus minimizing delay.

Policy-based Access

ZTNA enforces strict, pre-defined, dynamically adjusted policy-based access controls based on real-time assessments. Since these policies are immediately applicable and constantly updated, they enable swift authentication decisions.

Intelligent Caching

ZTNA stores authentication tokens and user credentials securely. This allows for rapid re-authentication without the need for a repeated full authentication process.

Therefore, zero trust, and without delay.

Why Should I Consider ZTNA?

Employing ZTNA offers several compelling benefits that make it an attractive option for modern enterprises:

Enhanced security

ZTNA minimizes the attack surface by ensuring that only authenticated and authorized users can access specific resources. Continuous verification and granular control significantly reduce the risk of data breaches and cyberattacks.

Improved user experience

Traditional security measures like VPNs can be cumbersome and slow, leading to a subpar user experience. ZTNA solutions provide seamless, secure access to applications, improving productivity, and keeping users happy.


As organizations grow and adopt hybrid work models, ZTNA offers the flexibility to scale security measures without compromising performance. This scalability is crucial for businesses looking to adapt to dynamic environments.

Cost savings

ZTNA reduces the need for extensive hardware and simplifies network management. Additionally, your improved security minimizes the financial impact of potential breaches.

Zero Trust is not just a buzzword; it’s a necessary evolution in the face of increasingly sophisticated cyber threats. Organizations that adopt ZTNA are better positioned to protect their assets and adapt to future challenges.

Bruce Schneier, internationally renowned security technologist

ZTNA vs. VPN – It’s Time for a Change

Virtual Private Networks (VPNs) have long been the go-to solution for secure remote access. However, they come with inherent limitations that make them less effective with remote users, and with more sophisticated threats looming. VPNs are limited in their security, performance, and management.


While VPNs create a secure tunnel between the user and the network, their centralized, implicitly trusting methods grant often unrestricted access to the entire network once the connection is established. Malicious actors can exploit this broad access. In contrast, ZTNA enforces strict – yet adaptive and resilient – access controls. This ensures that users can only access the resources they are explicitly authorized for.


VPNs can suffer from latency and bandwidth issues, particularly when multiple users connect simultaneously. ZTNA solutions offer more efficient access by connecting users directly to the applications they need, bypassing the bottlenecks associated with traditional VPNs. Further, ZTNA’s cloud-based and adaptive architecture makes it more scalable and better suited to support remote and hybrid work models than more traditional, centralized approaches.


Managing a VPN infrastructure can be complex and resource-intensive. ZTNA simplifies network management by centralizing access policies and leveraging cloud-based solutions. This makes it easier for IT teams to maintain and update security measures.

Transitioning from VPNs to a ZTNA model comes with investment and a potentially complex implementation. However, you shouldn’t have trouble getting users to adopt the system.

ZTNA vs. VPN – The User Experience

ZTNA offers a better overall user experience. Here’s why:

Traditional VPNs can sometimes lead to slower connection speeds and bottlenecks. This is especially true when there’s network congestion or when the VPN server is geographically distant from the user.

This latency can hinder productivity, causing frustration among users who rely on seamless data and application access. VPNs offer compromised security as well. VPNs rely on perimeter-based security solutions like firewalls to protect the entire network. Once breached, attackers can move laterally with relative ease. 

ZTNA provides a more optimized and streamlined experience. By employing the techniques discussed below, ZTNA ensures quicker authentication and connectivity. ZTNA systems continuously verify user and device credentials in the background without constant full re-authentication. This means that users will have fewer interruptions and a more fluid workflow. 

Additionally, ZTNA can use microsegmentation rather than perimeter-based security. Microsegmentation creates multiple, isolated network zones, minimizing the adverse impact of potential intrusions.

Furthermore, the security protocols of ZTNA—while more robust—are less obtrusive compared to VPNs. Users are less burdened by manual security checks, as ZTNA systems dynamically update access policies and adapt to emerging threats without requiring user intervention. This makes the network access experience not only faster but also more secure – a win-win.

How Does ZTNA Work?

ZTNA operates through a combination of advanced technologies and stringent security principles to ensure a secure network environment. Here’s a breakdown of how it works:

  1. Continuous authentication and authorization:

Users and devices must continually authenticate their credentials and confirm their authorization status to gain access to the network. This process involves multi-factor authentication (MFA), biometric verification, and other identity-proofing techniques.

  1. Least privilege Access:

ZTNA enforces the principle of least privilege, where users are granted the minimum level of access necessary to perform their duties. This restricted access minimizes the potential damage from a compromised account.

  1. Endpoint checking or posture management:

ZTNA continuously monitors device health and security posture before granting access. Devices that do not meet the security criteria are denied access to the network.

  1. Encryption (if part of an overall secure access service edge [SASE] solution):

Data is encrypted both in transit and at rest to protect sensitive information from being intercepted or compromised by unauthorized parties.

  1. Microsegmentation in advanced ZTNA cases:

The network is divided into smaller, isolated segments to limit the potential for lateral movement by a cyber attacker. Each segment is protected and access is strictly controlled, ensuring that users can only access the specific resources they need.

ZTNA and Microsegmentation – A Deeper Look

While your ZTNA journey can start without microsegmentation, ZTNA will be incomplete without it. Microsegmentation can be a key component of the Zero Trust model, providing an additional layer of security.

By dividing the network into smaller segments by using methods such as software-defined networking (SDN), next-generation firewalls (NGFWs), and other microsegmentation platforms, specialized microsegmentation platforms provide granular control and visibility. They often integrate with existing security tools.

Implementing microsegmentation techniques allows organizations to enforce granular access controls. It also helps organizations limit lateral movement across network elements, therefore limiting the potential impact of a breach.

The benefits of microsegmentation include:

  • Reduced attack surface. By isolating segments, microsegmentation minimizes the number of resources accessible to an attacker.
  • Enhanced visibility. IT teams gain better visibility into network activity, making it easier to identify and respond to threats.
  • Improved compliance. Microsegmentation helps organizations meet regulatory requirements by adequately protecting sensitive data.

Effective microsegmentation requires care in planning and execution. Define your segments based on sensitivity and function, establish policies for each segment, test, and roll out your new system. Then, you’ll enjoy a more rigorous, adaptive approach to potential security threats. 

Talk to Zayo about ZTNA

At Zayo, we understand the challenges and opportunities that come with implementing ZTNA. Our team of experts is here to help you navigate the complexities and ensure a successful deployment. Whether you’re looking to enhance your network security, improve user experience, or achieve greater scalability, Zayo has the solutions you need. Contact our sales team to get started.

A Guide to Secure Access Service Edge (SASE)

SASE is the combination of security and networking elements offered in a single package. Explore the benefits of SASE in this blog.

Learn more about ZTNA, SASE, and edge networking

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