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Private Browsers with Local AI: How to Route and Protect Domain Traffic

UUnknown

2026-02-14

10 min read

Protect internal domain traffic from local-AI browsers (like Puma) using DoH, split-horizon DNS, sovereign resolvers, MDM and mTLS controls.

Stop local-AI browsers from leaking domain traffic: a practical network and DNS playbook for 2026

Hook: Your security team is suddenly seeing unknown DNS endpoints, your compliance auditors ask where sensitive domain queries are routed, and developers using local-AI browsers like Puma insist the model runs fully on-device. In 2026 the reality is messy: local LLM-enabled browsers can keep inference local but still emit DNS and networking traffic that reveals internal domains, exposes telemetry, or bypasses enterprise controls.

This article gives technology leaders, devs and IT admins a step-by-step strategy to keep domain traffic private when employees adopt local-AI browsers. You'll get patterns, test commands and policy ideas that work across mobile, desktop and cloud—built on the latest 2025–2026 trends: DoH/DoQ ubiquity, Encrypted Client Hello (ECH) adoption, and new sovereign-cloud resolver offerings such as the AWS European Sovereign Cloud.

Key takeaways up front

Local AI browsers (for example Puma on iOS/Android) can still leak DNS metadata unless you control the resolver path.
DNS-over-HTTPS (DoH) and DNS-over-QUIC (DoQ) are now mainstream; blocking port 53 is necessary but not sufficient to stop leakage.
Split-horizon DNS (private vs public views) plus enterprise-managed DoH resolvers are the most practical pattern to protect internal records.
Adopt centralized enterprise policies—MDM, per-app VPNs, and DNS allow-listing—for mobile local-AI browsers.

Why local AI browsers still create a DNS problem

Local model execution (the 'Local' in local AI browser) reduces cloud telemetry risk, but the browser still issues HTTP, TLS and DNS queries for the pages and resources it loads. Those DNS queries can:

Reveal internal hostnames, project names and environment patterns to third-party resolvers.
Bypass enterprise filtering and logging if an app uses hard-coded DoH endpoints or tunnels (common with some privacy-first browsers).
Expose queries to sovereign risks if device resolvers ping overseas providers, complicating EU/UK data residency demands.

2026 context: what changed recently

DoH/DoQ is default in many browsers and some mobile SDKs; more apps encrypt DNS to evade tampering.
Encrypted ClientHello (ECH) adoption increased in 2025, which hides SNI and complicates on-path allow-listing of TLS endpoints used by DoH providers.
Cloud vendors introduced sovereign-resolver and private-cloud DNS options (AWS European Sovereign Cloud and region-specific resolvers) to satisfy compliance.
Companies are deploying internal DoH resolvers or secure resolver clusters rather than relying on public resolvers to retain control.

High-level architecture: two practical patterns

Choose one of two patterns depending on scale and regulatory pressure:

1) Enterprise-managed resolver + network enforcement (recommended)

Run a fleet of DoH/DoQ resolvers inside your cloud or sovereign cloud (Route 53 Resolver, Azure Private Resolver, Cloud DNS Resolver in private VPCs).
Enforce DNS egress rules at the edge: block port 53 and non-approved DoH endpoints using firewall, SASE or CASB policies.
Provide high-availability endpoints and mTLS for DoH clients; publish CA pins and use client certs for mutual TLS where possible.
Use split-horizon to serve internal records to enterprise clients while returning public records for external clients.

2) Zero-trust with per-app VPNs and split DNS for sensitive workloads

For BYOD or mobile local-AI use, require an MDM-managed per-app VPN that forces all DNS to your resolver.
Assign internal-only zones (corp.internal, svc.cluster.local) to the private resolver and ensure clients never send those names to the public Internet.
Use SASE/SSE with DNS filtering and logging for remote users where a private resolver can't be enforced locally.

Implementation details: buildable playbook

Below are pragmatic, testable steps you can operationalize this week.

Step 1 — Inventory: find where queries are going

Start by discovering whether local-AI browsers use local or remote resolvers.

On desktop/laptop: monitor with tcpdump to capture DNS traffic.

sudo tcpdump -n -i any '(port 53 or tcp port 853 or tcp port 443) and host not 127.0.0.1'

For DoH-specific traces, use curl to simulate a DoH request and inspect the connection:

curl --doh-url 'https://1.1.1.1/dns-query' -sS 'https://example.com' --trace-ascii -

On mobile, capture traffic via an MDM-managed tunnel or use a packet-capture app during device testing. Look for connections to known DoH/DoQ providers (Cloudflare, Google, Quad9, NextDNS), and watch for direct connections to your internal resolver.

Step 2 — Block unmanaged resolvers at the network edge

Block UDP/TCP port 53 egress to the Internet from your corporate network and block known public DoH endpoints unless explicitly allowed. In practice you must:

Identify the IP ranges of approved DoH resolvers and allow only those ranges.
Block outbound TLS connections to unapproved endpoints using SASE or firewall rules; be cautious with ECH (see below).

Step 3 — Deploy an enterprise DoH/DoQ resolver fleet

Options:

Use managed private resolvers in your cloud provider's sovereign region (for example, AWS European Sovereign Cloud) to retain data residency guarantees.
Deploy open-source resolvers (CoreDNS, Knot Resolver, Unbound) fronted with an HTTP/QUIC gateway for DoH/DoQ.
Offer mutual TLS to authenticate device clients; rotate client certs periodically via your PKI/MDM.

Example: run Knot Resolver in your VPC, expose DoH with an authenticated ingress, and register the DoH endpoint with your MDM policies for mobile apps.

Step 4 — Implement split-horizon DNS

Split-horizon DNS (also called split-view) isolates internal names from public resolvers. Two practical ways to implement:

Zone-based split: Maintain private zones (internal.corp) on your enterprise resolver and only serve them to authenticated clients.
Conditional forwarding: Use a resolver that forwards specific suffixes to internal name servers (for example, Kubernetes cluster DNS or on-prem Active Directory DNS).

For Kubernetes workloads, use CoreDNS with conditional forwarding or a private Route 53 zone linked to your VPC. For Windows AD environments, ensure AD DNS remains authoritative for internal names and is reachable only via your resolver fleet.

Step 5 — Mobile & Puma-specific guidance

Local-AI mobile browsers like Puma run models locally but still call external domains for updates, resources and some telemetry. For mobile devices:

Enroll devices in MDM and push per-app VPN or forced DNS settings.
Use app allow-listing for DoH endpoints. Where the app allows custom resolvers, distribute your enterprise DoH endpoint via managed configuration.
Block unapproved DoH endpoints at the network level and in the device management policy.

On iOS and Android, modern MDMs can set per-app VPNs and restrict network traffic so Puma or other local-AI browsers only use the enterprise resolver for DNS.

Step 6 — Handle ECH and evasive DoH usage

ECH hides SNI, making TLS allow-listing based on hostname less reliable. In 2026 this is a real operational challenge. Options:

Prefer IP-allow-listing for known resolver endpoints combined with mTLS client authentication so only enterprise clients succeed.
Run your DoH endpoints within your sovereign cloud so traffic never leaves the approved jurisdiction.
Use certificate-based allow-listing and pinning where possible; issue device client certs via MDM to ensure only managed devices can reach the resolver.

In short: don’t rely on SNI for allow-lists—use mutual TLS and IP+cert controls. See guidance on avoiding metadata leaks in How to Safely Let AI Routers Access Your Video Library Without Leaking Content.

Step 7 — Audit and testing

Automate periodic checks:

Continuous monitoring: log all DNS queries at resolver, use SIEM to flag external destinations for internal names.
Red-team test: deploy unmanaged device and local-AI browser to see if it can bypass DNS controls. Use portable comm testers and network kits to assist capture and verification.
Query tests: run these commands from a device to confirm resolver behavior:

# Test standard DNS
dig @your-resolver internal-service.corp A

# Test DoH via curl
curl --doh-url 'https://doh.yourcompany.example/dns-query' 'https://example-internal.corp' -v

# Capture egress connections
sudo tcpdump -n -i any '(port 53 or port 853 or port 443)'

Policy controls and governance

Technology alone isn't sufficient—wrap these controls in clear policies:

Acceptable browser list: Allow only vetted local-AI browsers that support MDM-managed DNS configuration.
Per-app network policy: Mandatory per-app VPN for any browser that can be used to access internal apps.
Resolver SLA and availability: Ensure enterprise DoH endpoints have an SLA, monitoring and multi-region redundancy (consider sovereign-region replicas).
Logging and retention: Log query metadata but keep the content minimal; redact or aggregate where necessary to meet privacy rules. For privacy-minded logging patterns, consider advice from whistleblower and source-protection playbooks like Whistleblower Programs 2.0.
Threat response: Define automated responses for detected exfiltration or queries to suspicious DoH endpoints.

Advanced strategies for 2026 and beyond

Sovereign-cloud resolver deployments

If you operate under EU/UK/data-residency constraints, run resolvers in the corresponding sovereign cloud region (for example, AWS European Sovereign Cloud). This gives legal assurances and limits exposure when devices travel internationally.

mTLS for DoH + device PKI

Mutual TLS between client and resolver is one of the most reliable controls. Provision short-lived device certificates via your MDM or PKI automation. Rotate and revoke as part of device lifecycle.

Granular split-horizon with service mesh integration

For cloud-native teams, integrate split-horizon DNS with service meshes (e.g., Istio, Linkerd) so that internal service discovery remains entirely within the mesh and never requires public DNS resolution.

Telemetry minimization

For compliance and privacy, keep telemetry at a minimum. Collect only metadata needed for security—avoid storing full query strings for longer than necessary and implement privacy-by-design in your resolver stack. For broader operational evidence and preservation guidance, see Operational Playbook: Evidence Capture and Preservation at Edge Networks.

Real-world example: how AcmeCorp stopped local-AI leakage

Situation: AcmeCorp’s developers started using Puma and another privacy-first browser on mobile devices. Some apps began issuing DoH queries to public resolvers—leaking staging hostnames.

Actions taken:

Immediate network rule: block outbound UDP/TCP 53 and restrict outbound 443/QUIC to approved resolver IP ranges.
Deploy: a high-availability DoH/DoQ pair in a sovereign cloud region with mutual TLS.
MDM policy: enroll devices and push per-app VPN configuration to Puma, plus an enterprise DoH endpoint.
Monitoring: forward query logs to SIEM, watch for internal suffixes leaving the resolver.

Result: within two weeks, external leaks stopped. Developer friction was reduced because the enterprise resolver returned internal names correctly (no broken links), and the security team regained visibility and compliance posture.

Checklist: quick operational runbook

Inventory browsers and apps that enable local AI (Puma, Brave variants, others).
Block port 53 egress from corp networks and restrict DoH providers to approved IP ranges.
Deploy enterprise DoH/DoQ resolvers in appropriate sovereign regions.
Implement split-horizon DNS for internal zones and conditional forwarding to internal name servers.
Use MDM to enforce per-app VPNs and push enterprise resolver settings to mobile browsers.
Authenticate clients with mTLS and rotate device certs via PKI automation.
Log, alert, and test continuously (tcpdump, dig, curl DoH requests).

Final thoughts and recommended next steps

Local AI browsers like Puma deliver great user privacy and responsiveness, but they shift the risk surface to network metadata. In 2026, the defenders' playbook is to combine enterprise-managed DoH/DoQ, split-horizon DNS, and strong device/PKI controls—backed by MDM and SASE—to prevent domain traffic leakage without breaking developer workflows.

Start with inventory and blocking unmanaged resolvers this week, then roll out a resilient DoH fleet and MDM controls over the next quarter. Prefer sovereign-cloud resolvers where regulation requires it, and adopt mTLS for authenticated resolver sessions.

Actionable next step

Run a quick test within 48 hours: use tcpdump on a corporate laptop while a tester opens a local-AI browser (Puma). Look for unexpected DoH endpoints, then apply a temporary edge rule to block that endpoint and observe whether services break. Use the results to build your resolver allow-list and MDM push configuration.

Call to action: Need a tailored plan for your environment? Contact your domains and DNS team to run a 2-week leakage assessment and a DoH hardened resolver proof-of-concept. Protect your internal domains before the next audit.

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