What is a URL Category?

A URL category is a predefined or custom classification – such as Gambling, Social Network, or Malware Sites – assigned to a URL. Versa Operating System (VOS) devices look up the category from a locally cached database or a larger cloud-based database, then use it as match criteria in URL-filtering, security, and traffic-steering policies.

Key takeaways

• URL categories classify web destinations for filtering and steering policy.
• VOS ships predefined categories and supports custom, pattern-based ones.
• A local database holds up to 20 million URLs; the cloud database holds 2B+.
• Category and reputation actions are evaluated together, most severe wins.
• SD-WAN traffic steering can route flows differently based on URL category.

On this page: Why it matters · How it works · Types · URL categories & Versa · FAQ

Why are URL categories important?

Blocking or steering traffic by IP address or hostname alone does not scale – the web has billions of destinations, and new ones appear constantly. URL categories abstract that problem: instead of maintaining lists of individual sites, an administrator writes one rule against a category, such as Gambling or Adult and Pornography, and every URL classified into it is covered automatically, including sites that did not exist when the rule was written.

The same abstraction matters beyond blocking. Security teams use categories such as Malware Sites, Phishing and Other Frauds, and Bot Nets to drive automatic threat response, and network teams use categories to influence path selection – sending SaaS and business traffic over a preferred link while treating discretionary categories differently. Categorization is what turns a firewall or SD-WAN policy from a list of addresses into a policy about the kind of traffic crossing the network.

What is a URL category?

Every category is a named group of URLs sharing a topic or risk profile – Gambling, Social Network, Government, and dozens more are predefined and maintained by Versa through security package (SPack) updates. A VOS device classifies a requested URL by checking its local database, which can cache up to 20 million entries, and can fall back to a cloud-based database of more than 2 billion categorized URLs for real-time lookup when a URL is not cached locally.

Category lookups happen alongside URL reputation lookups – a separate risk rating from Trustworthy to High Risk – and policies can match on either or both. Because Layer 7 inspection needs a few packets before an application or URL is identified, VOS also maintains a URL category cache keyed on server IP address and port, so subsequent packets in the same flow are steered correctly from the first packet onward.

Types of URL categories

VOS distinguishes two kinds of category. Predefined categories are the built-in set VOS ships and updates automatically – dozens of categories such as Business and Economy, Gambling, Games, Generative AI, Hacking, Social Network, and Malware Sites, each with its own description and example sites, viewable and searchable from Director’s predefined objects list.

Custom URL categories are administrator-defined: matched by fixed strings or regular-expression patterns against the normalized URL (protocol prefixes are stripped before matching), optionally built from an uploaded file of patterns, and each assigned a confidence value from 1–100 used to break ties when a URL matches more than one category. Custom categories can also override a predefined category’s classification for specific URLs, and both types can carry an associated reputation.

URL categories & Versa

URL categories are configured as objects and consumed as match criteria across the platform. URL filtering uses category action maps – rules that assign a session or packet action, or a captive-portal response, to one or more predefined or custom categories – evaluated alongside reputation action maps, with VOS enforcing whichever action is more severe when both apply. SD-WAN policy rules add a URL tab where categories serve as traffic-steering match criteria, requiring the URL category cache to be enabled so flows steer correctly from the first packet. The same category objects and workflow apply whether the deployment is Secure SD-WAN or NGFW-focused.

Frequently asked questions

What is the difference between a predefined and a custom URL category?

Predefined categories are built into VOS and updated through security package updates; administrators cannot edit their membership directly. Custom categories are administrator-defined using string or regex patterns, can override predefined classifications for specific URLs, and carry a configurable confidence value.

How does VOS decide which category applies when a URL matches more than one?

Each custom URL category has a confidence value from 1 through 100. When a URL matches multiple categories, VOS applies the category with the higher confidence value, letting administrators explicitly rank overlapping or overriding rules.

How does URL category differ from URL reputation?

URL category describes a URL’s topic or content type, such as Gambling or Shopping. URL reputation is a separate risk rating, from Trustworthy to High Risk. Policies can match on category, reputation, or both, and VOS enforces the more severe action when both rules apply to the same URL.

Can URL categories be used for something other than blocking access?

Yes. Beyond URL-filtering block, allow, and captive-portal actions, SD-WAN traffic-steering policy can match on URL category to route flows over different paths – for example, steering categorized SaaS or business traffic differently from discretionary browsing.

Where does VOS get its URL category data from?

VOS devices maintain a local database of up to 20 million categorized URLs and can query a cloud-based database of more than 2 billion URLs in real time for entries not yet cached locally, keeping classifications current as new sites appear.

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