Implementing Zero Trust DNS with NextDNS
Overview
NextDNS is a cloud-based DNS resolver that provides encrypted DNS resolution (DNS-over-HTTPS and DNS-over-TLS), real-time threat intelligence blocking, ad and tracker filtering, and granular DNS policy enforcement. In a zero trust architecture, DNS is a critical control point -- every network connection begins with a DNS query, making DNS filtering an effective layer for blocking malicious domains, preventing data exfiltration via DNS tunneling, enforcing acceptable use policies, and gaining visibility into all network communications. NextDNS processes queries using threat intelligence feeds containing millions of malicious domains updated in real-time, blocks cryptojacking and phishing domains, detects DNS rebinding attacks, and supports CNAME cloaking protection. For enterprise environments, Microsoft's Zero Trust DNS (ZTDNS) feature on Windows 11 extends this concept by enforcing that endpoints can only resolve domains through approved protected DNS servers.
When to Use
- When deploying or configuring implementing zero trust dns with nextdns capabilities in your environment
- When establishing security controls aligned to compliance requirements
- When building or improving security architecture for this domain
- When conducting security assessments that require this implementation
Prerequisites
- NextDNS account (free tier: 300,000 queries/month; Pro: unlimited)
- Network devices supporting DoH or DoT configuration
- Administrative access to endpoint DNS settings
- Understanding of DNS protocol and resolution chain
- Familiarity with organizational acceptable use policies
Architecture
Endpoint Device
|
DNS Query (Encrypted)
|
+----+----+
| DoH/DoT | (DNS-over-HTTPS or DNS-over-TLS)
| Tunnel |
+----+----+
|
+----+----+
| NextDNS |
| Resolver |
+----+----+
|
+----+----+------+--------+
| | | |
Threat Ad/Tracker Privacy Parental
Intel Blocklists Controls Controls
Check Check Check Check
| | | |
+----+----+------+--------+
|
ALLOW or BLOCK
|
Response to Endpoint
Configuration Setup
NextDNS Profile Configuration
Dashboard: https://my.nextdns.io
Configuration ID: abc123 (unique per profile)
Endpoints:
DNS-over-HTTPS: https://dns.nextdns.io/abc123
DNS-over-TLS: abc123.dns.nextdns.io
DNS-over-QUIC: quic://abc123.dns.nextdns.io
IPv4: 45.90.28.x, 45.90.30.x (linked to config)
IPv6: 2a07:a8c0::xx, 2a07:a8c1::xx
Security Settings
Security Tab Configuration:
[x] Threat Intelligence Feeds - Block domains from curated threat feeds
[x] AI-Driven Threat Detection - Machine learning-based detection
[x] Google Safe Browsing - Cross-reference with Google's threat database
[x] Cryptojacking Protection - Block crypto mining domains
[x] DNS Rebinding Protection - Prevent DNS rebinding attacks
[x] IDN Homograph Attacks - Block internationalized domain name attacks
[x] Typosquatting Protection - Block common typosquatting domains
[x] DGA Protection - Block domain generation algorithm domains
[x] NRD (Newly Registered Domains) - Block domains < 30 days old
[x] DDNS (Dynamic DNS) - Block dynamic DNS services
[x] Parked Domains - Block parked/unused domains
[x] CSAM - Block child sexual abuse material domains
Privacy Settings
Privacy Tab Configuration:
Blocklists:
[x] NextDNS Ads & Trackers Blocklist
[x] OISD (Full)
[x] EasyPrivacy
[x] AdGuard DNS Filter
Native Tracking Protection:
[x] Block Windows telemetry
[x] Block Apple telemetry
[x] Block Samsung telemetry
[x] Block Xiaomi telemetry
[x] Block Huawei telemetry
[x] Block Roku telemetry
[x] Block Sonos telemetry
[x] Block Disguised Third-Party Trackers (CNAME cloaking)
[x] Allow Affiliate & Tracking Links (optional, for business)
Allowlist and Denylist
Allowlist (domains that bypass all blocking):
- login.microsoftonline.com
- graph.microsoft.com
- *.company.com
Denylist (always blocked regardless of other settings):
- known-malicious-domain.com
- unauthorized-cloud-storage.com
- personal-email-provider.com (if policy requires)
Endpoint Deployment
Linux (systemd-resolved)
sudo tee /etc/systemd/resolved.conf << 'EOF'
[Resolve]
DNS=45.90.28.x#abc123.dns.nextdns.io
DNS=45.90.30.x#abc123.dns.nextdns.io
DNS=2a07:a8c0::xx#abc123.dns.nextdns.io
DNS=2a07:a8c1::xx#abc123.dns.nextdns.io
DNSOverTLS=yes
Domains=~.
EOF
sudo systemctl restart systemd-resolved
resolvectl status
resolvectl query example.com
Linux (NextDNS CLI)
sh -c 'sh -e $(curl -sL https://nextdns.io/install)'
sudo nextdns install \
-config abc123 \
-report-client-info \
-auto-activate
nextdns status
nextdns log
macOS
brew install nextdns/tap/nextdns
sudo nextdns install \
-config abc123 \
-report-client-info
Windows
# Install NextDNS CLI for Windows
# Download from: https://nextdns.io/download/windows
# Or configure DoH natively (Windows 11)
# Settings > Network & Internet > Ethernet/Wi-Fi > DNS
# Preferred DNS: 45.90.28.x
# DNS over HTTPS: On (Manual template)
# DoH Template: https://dns.nextdns.io/abc123
# PowerShell: Configure DoH
Set-DnsClientDohServerAddress -ServerAddress "45.90.28.x" `
-DohTemplate "https://dns.nextdns.io/abc123" `
-AllowFallbackToUdp $false `
-AutoUpgrade $true
Router-Level Configuration
# Most routers support custom DNS servers
# For DoH/DoT-capable routers (pfSense, OPNsense, OpenWrt):
# pfSense DNS Resolver (Unbound):
# Services > DNS Resolver > Custom Options:
server:
forward-zone:
name: "."
forward-tls-upstream: yes
forward-addr: 45.90.28.x@853#abc123.dns.nextdns.io
forward-addr: 45.90.30.x@853#abc123.dns.nextdns.io
# OpenWrt (using https-dns-proxy):
opkg update && opkg install https-dns-proxy
uci set https-dns-proxy.default.resolver_url='https://dns.nextdns.io/abc123'
uci commit https-dns-proxy
/etc/init.d/https-dns-proxy restart
Mobile Devices
iOS:
Install NextDNS app from App Store
Or: Settings > General > VPN & Device Management
Install NextDNS configuration profile
Android:
Settings > Network > Private DNS
DNS Provider: abc123.dns.nextdns.io
Or: Install NextDNS app from Play Store
Microsoft Zero Trust DNS (Windows 11)
For enterprise Windows environments, Microsoft's ZTDNS enforces that endpoints can only communicate with domains resolved through approved DNS servers.
# Enable ZTDNS (Windows 11 23H2+)
# Requires Windows Defender Firewall in enforcing mode
# Configure Protected DNS Servers via Group Policy:
# Computer Configuration > Administrative Templates > Network > DNS Client
# > Configure DNS over HTTPS (DoH) name resolution
# > Protected DNS servers: https://dns.nextdns.io/abc123
# Windows Firewall blocks all traffic to domains not resolved
# through the protected DNS server
Monitoring and Analytics
Log Analysis
NextDNS Analytics Dashboard provides:
- Total queries over time
- Blocked queries by category
- Top domains (allowed and blocked)
- Top blocked reasons (threat, ad, tracker)
- Device-level breakdown
- Geographic query distribution
Log Settings:
Retention: 1 hour / 6 hours / 1 day / 1 week / 1 month / 3 months / 1 year / 2 years
Storage Location: US / EU / UK / Switzerland
Logging: [ ] Enable / [ ] Disable
API Integration
curl -H "X-Api-Key: your-api-key" \
"https://api.nextdns.io/profiles/abc123/analytics/domains?from=-24h"
curl -H "X-Api-Key: your-api-key" \
"https://api.nextdns.io/profiles/abc123/analytics/domains?from=-24h&status=blocked"
curl -H "X-Api-Key: your-api-key" \
"https://api.nextdns.io/profiles/abc123/logs?from=-1h" \
| jq '.data[] | select(.status == "blocked")'
Zero Trust DNS Policy Framework
Policy Tiers
Tier 1 - Security (Mandatory for all):
- Threat intelligence blocking
- Cryptojacking protection
- DNS rebinding protection
- DGA detection
- NRD blocking (< 30 days)
Tier 2 - Privacy (Recommended):
- Tracker blocking
- Native telemetry blocking
- CNAME cloaking protection
Tier 3 - Compliance (Organization-specific):
- Category-based blocking
- Custom allowlists/denylists
- Time-based access policies
- Log retention per regulatory requirements
Security Best Practices
- Enforce encrypted DNS: Block plaintext DNS (port 53 UDP/TCP) at the firewall
- Use NextDNS CLI on endpoints: Ensures per-device identification and logging
- Enable NRD blocking: Newly registered domains are overwhelmingly malicious
- Block DNS-over-HTTPS bypass: Ensure browsers use system DNS, not built-in DoH
- Review blocklists quarterly: Remove false positives, add organizational blocks
- Enable CNAME cloaking protection: Prevents tracker evasion via CNAME records
- Set appropriate log retention: Balance privacy with forensic needs (90 days recommended)
- Monitor for DNS tunneling: Watch for unusual query patterns and high entropy domains
- Deploy at router level: Catches all devices including IoT and unmanaged endpoints
- Combine with endpoint DNS: Defense in depth with both router and per-device filtering
References
