You’re at your desk when the call comes in: “Nobody can access the client portal.” Your stomach drops. Is it DNS? Of course it’s DNS. It’s always DNS.

When DNS resolution fails in your Meraki network, everything grinds to a halt. Users panic. Managers hover. And you’re stuck trying to diagnose a problem that could stem from dozens of different sources.

Diagnosing DNS resolution failures in a Meraki network doesn’t have to be a nightmare. With the right troubleshooting approach, you can quickly identify whether the issue lies with your Meraki configuration, upstream DNS servers, or something else entirely.

But before we dive into the step-by-step diagnosis process, there’s one critical mistake most network admins make that extends downtime by hours…

Understanding DNS Resolution in Meraki Networks

A. Key components of Meraki DNS architecture

Meraki networks handle DNS differently than your typical network setup. At its core, the architecture includes:

• Security appliance (MX): Acts as the DNS forwarder for your entire network
• Cloud-based management: Controls DNS settings through dashboard policies
• Client devices: Receive DNS server assignments via DHCP
• Conditional forwarding: Routes specific domain requests to designated servers

The beauty of Meraki’s approach is that everything’s managed from a single dashboard. No more jumping between different interfaces or command lines to troubleshoot DNS issues.

B. Common DNS resolution failure scenarios

DNS problems in Meraki networks typically fall into a few buckets:

• Incorrect DNS server assignments: You set the wrong DNS servers or they’re unreachable
• DHCP misconfiguration: Client devices receive bad DNS information
• Split-tunnel VPN issues: DNS queries get sent through the wrong tunnel
• Firewall rules blocking DNS: Security settings preventing UDP/TCP port 53 traffic
• Dashboard policy conflicts: Multiple policies fighting over DNS settings

I’ve seen networks completely grind to a halt because someone blocked DNS traffic with an overzealous security rule. Simple mistake, massive headache.

C. Impact of DNS failures on network performance

When DNS breaks in a Meraki network, the ripple effects are immediate:

• Users report “internet is down” even though connectivity exists
• Web applications return strange errors rather than clean timeouts
• IoT devices stop communicating with cloud services
• Mobile devices drain battery faster from repeated connection attempts
• VoIP and video calls suffer quality issues or fail to connect

The tricky part? These symptoms often masquerade as bandwidth or application problems, sending you down the wrong troubleshooting path.

D. How Meraki handles DNS queries differently from traditional networks

Meraki’s approach to DNS stands apart from traditional networks in several key ways:

• Centralized control: All DNS settings pushed from cloud dashboard
• Layer 7 filtering: Can inspect and block DNS requests based on content
• Client fingerprinting: Identifies devices making suspicious DNS requests
• Automatic DNS caching: Improves performance without manual configuration
• Intelligent DNS proxy: Can intercept, inspect, and redirect DNS traffic

This approach gives admins more visibility and control but requires understanding these differences when diagnosing issues. Many traditional DNS troubleshooting methods need adaptation in Meraki environments.

Initial Troubleshooting Steps

A. Verifying basic connectivity

DNS problems often masquerade as connectivity issues. Before diving deep, check if your devices can actually reach the network:

1. Check if the device connects to the SSID (for wireless) or registers on the switch port (for wired)
2. Verify IP address assignment – run ipconfig (Windows) or ifconfig/ip addr (Mac/Linux)
3. Try pinging the gateway – if this fails, you don’t have basic connectivity
4. Check if you can ping external IPs like 8.8.8.8 – success here means internet works but DNS is failing

B. Checking client device configurations

DNS troubles frequently hide in device settings. Get your detective hat on:

• Look at network adapter settings – are DNS servers statically configured or using DHCP?
• Check for VPN software that might hijack DNS queries
• Examine hosts files that could override normal DNS resolution
• Review browser extensions that might interfere with DNS (especially “privacy” tools)

The strangest DNS issues I’ve seen were from forgotten proxy settings or misconfigured security software.

C. Testing DNS resolution with command-line tools

Command-line tools cut through the confusion fast:

nslookup google.com
dig google.com

These commands show exactly which DNS server responded and what records were returned. Common problems you’ll spot:

• “Server failed” responses
• Unusual timeouts
• Wrong IP addresses returned
• Correct lookups for some domains but not others

Try both internal and external domains to isolate where the failure happens.

D. Examining Meraki dashboard alerts related to DNS

The Meraki dashboard is literally waving red flags at you:

• Check “Alerting & Monitoring” for DNS-related notifications
• Review the “Security events” section for blocked DNS requests
• Examine content filtering logs for incorrectly blocked domains
• Look at client connection history for pattern identification

Pay special attention to security appliance settings that might block specific DNS traffic types.

E. Confirming upstream DNS server availability

Your Meraki network is only as good as its upstream DNS:

• Ping and test your configured DNS servers
• Check if your ISP is experiencing DNS outages
• Verify that firewall rules allow DNS traffic (UDP/TCP port 53)
• Test alternate public DNS servers like 8.8.8.8 (Google) or 1.1.1.1 (Cloudflare)

Sometimes the fix is as simple as switching to more reliable DNS servers in your Meraki DHCP settings.

Advanced Diagnostic Techniques

A. Analyzing Meraki event logs for DNS failures

DNS issues can hide in plain sight, but Meraki event logs are like that flashlight you needed all along. Jump into your Meraki dashboard and navigate to Network-wide ＞ Event log.

Filter for “DNS” related events and you’ll see patterns emerge. Look for recurring failures from specific clients or at particular times. That weird spike at 3 PM every day? Probably not a coincidence.

The key events to watch for:

• “DNS server not responding”
• “DNS request timeout”
• “DNS resolution failed”

When you spot these, note the device, time, and which DNS server was targeted. Cross-reference these with user complaints and you’ll often find they line up perfectly.

Pro tip: Export these logs to CSV for deeper analysis in your tool of choice. Sometimes the bigger picture only emerges when you’re looking at data over days or weeks.

B. Using packet capture to trace DNS queries

When logs don’t tell the whole story, packet captures will. On your Meraki dashboard, head to Wireless ＞ Packet capture or Network-wide ＞ Packet capture.

Set up a capture with these filters:

• Protocol: UDP
• Port: 53 (standard DNS)
• Client IP: The troubled device

Start the capture during an active problem period. What you’re hunting for:

• Are DNS queries actually leaving your network?
• Which DNS servers are being queried?
• Is there any response coming back?

A healthy DNS query/response will show an outbound request followed quickly by an inbound response. If you see queries with no responses, you’ve found your smoking gun.

The beauty of packet captures is they don’t lie. They show exactly what’s happening on the wire, not what a device thinks is happening.

C. Interpreting DNS response codes

DNS servers talk in codes, and understanding them is critical to solving your problems.

Common response codes you’ll encounter:

Code	Name	What it really means
0	NOERROR	Everything’s fine (query successful)
1	FORMERR	Format error (malformed query)
2	SERVFAIL	Server failure (DNS server is having issues)
3	NXDOMAIN	Non-existent domain (the domain doesn’t exist)
5	REFUSED	Query refused (server won’t process this request)

SERVFAIL is particularly tricky – it could mean your DNS server can’t reach its upstream servers, or it’s overwhelmed. NXDOMAIN sounds bad but might just mean a typo in the domain name.

When troubleshooting, focus on patterns. One SERVFAIL is a blip. Consistent SERVFAIL responses point to deeper infrastructure issues.

D. Troubleshooting DNS caching issues

DNS caches can be both your best friend and worst enemy. When they work, they speed everything up. When they’re stuck with bad data, they’re infuriating.

First, check your Meraki caching settings under Security & SD-WAN ＞ Configure ＞ Content filtering. Is local DNS caching enabled? This could be preserving outdated records.

Common cache-related issues:

• Cached negative responses (system remembers a domain doesn’t exist)
• Outdated IP mappings after a server migration
• Inconsistent results across devices (some cached, some not)

To flush the Meraki DNS cache, you can temporarily disable DNS caching and then re-enable it. For client-side issues, the classic “flush your DNS” solution works:

Windows: ipconfig /flushdns
Mac: sudo killall -HUP mDNSResponder
Linux: sudo systemd-resolve --flush-caches

Remember that caching happens at multiple levels – browsers, operating systems, local DNS servers, and ISPs all maintain caches. Sometimes you need to clear them all to truly start fresh.

Meraki-Specific DNS Configuration Issues

Dashboard DNS Settings Review

DNS issues in your Meraki network? Start with the dashboard. I’ve seen countless network engineers waste hours troubleshooting when the answer was sitting right in their dashboard settings.

Navigate to Security & SD-WAN ＞ Configure ＞ Addressing & VLANS. Check if your DNS servers are correctly configured. Meraki devices prioritize these settings over DHCP-provided DNS servers.

Common mistakes include:

• Using outdated DNS servers
• Mixing internal and external DNS IPs
• Forgetting to click “Save” after changes

If you’re running a split DNS setup, double-check both internal and external server entries. Typos happen to the best of us—a missing digit in an IP address can bring your resolution to a grinding halt.

DHCP Server Configuration Verification

Your DHCP server might be sabotaging your DNS resolution without you knowing it. Head to Network-wide ＞ Configure ＞ DHCP.

Check these DHCP settings:

• DNS server IPs match your intended configuration
• DHCP lease times aren’t too short (causing frequent renewals)
• Option 6 settings aren’t conflicting with dashboard DNS settings

Pro tip: If you’re using custom DHCP options, make sure Option 15 (domain name) aligns with your DNS search domains. Mismatches here lead to those weird “can ping by IP but not by name” scenarios.

Many admins forget that Meraki provides different DHCP settings per VLAN. A DNS server that works for your corporate VLAN might be unreachable from your guest network.

DNS Security Policies Examination

DNS filters causing trouble? They often do.

In your dashboard, check Security & SD-WAN ＞ Configure ＞ Content Filtering. The DNS-based security policies might be blocking legitimate requests.

When examining DNS security settings, look for:

• Overly aggressive category blocks
• Custom blocklists catching legitimate domains
• Misconfigured allowlists

A dead giveaway: if users report they can access sites via IP but not domain names, your DNS security is likely the culprit.

Don’t forget to check your Umbrella integration if you’re using it. The hand-off between Meraki and Umbrella can get messy, especially when policies conflict.

Client VPN DNS Resolution Problems

VPN DNS issues are in a league of their own. Go to Security & SD-WAN ＞ Configure ＞ Client VPN.

Most VPN DNS problems stem from:

• Split-tunnel configurations not properly routing DNS requests
• “Use same DNS as MX” enabled when it shouldn’t be
• Custom DNS servers unreachable across the tunnel

If your remote users can connect but can’t resolve internal resources, check the “Split DNS” settings. You need to explicitly define which domains should resolve through the tunnel.

Another gotcha: check if your firewall rules are allowing DNS traffic from VPN clients. It’s surprisingly easy to block UDP/53 accidentally.

Local DNS Record Management

Meraki networks typically rely on external DNS servers, but you can add local overrides.

Navigate to Security & SD-WAN ＞ Configure ＞ Local DNS. Here you can create:

• Static A records for critical internal resources
• CNAME records for aliasing services
• Custom DNS entries for testing

These local records override external DNS responses, which is perfect for troubleshooting or creating internal shortcuts.

Remember that local DNS records only work for clients using the MX as their DNS server. If clients point elsewhere, these records won’t help.

Keep your local DNS database clean. Outdated entries cause just as many problems as missing ones.

Resolving Common DNS Problems

Fixing DNS Server Misconfigurations

DNS issues in Meraki networks often boil down to server misconfigurations. Check your primary and secondary DNS server settings first. Are they pointing to the right places? I’ve seen countless networks where someone accidentally typed 8.8.4.4 instead of 8.8.8.8 for Google DNS.

Go to Security & SD-WAN ＞ Configure ＞ DHCP to verify your DNS server settings. If you’re using local DNS servers, make sure they’re actually online. Ping them from within the network to confirm connectivity.

And don’t forget about DNS caching! Sometimes the problem isn’t current settings but outdated cached entries. Clear the DNS cache on problem devices or set shorter TTL values to refresh DNS information more frequently.

Addressing DNS Forwarding Issues

DNS forwarding gone wrong creates a special kind of headache. When your Meraki device forwards DNS queries to upstream servers that aren’t responding, everything grinds to a halt.

Set up proper failover by configuring multiple forwarding servers. Your forwarding hierarchy should be:

• Primary internal DNS server
• Secondary internal DNS server
• External DNS provider (like Cloudflare 1.1.1.1)

Check your forwarding timeout settings too. If set too low, queries might fail before upstream servers have time to respond.

Resolving Conditional Forwarding Failures

Conditional forwarding lets you route specific domain queries to different DNS servers. But when it breaks, it’s confusing as heck.

Common failures happen when:

• The target DNS server is unreachable
• Domain patterns are misconfigured
• Recursive lookups are disabled

Test conditional forwarding rules individually with nslookup domain-name specified-server to pinpoint which rule is failing.

Managing Split-Horizon DNS Challenges

Split-horizon DNS serves different answers depending on where the query comes from. Cool feature, troubleshooting nightmare.

If internal users can’t reach resources by name but external users can, your split-horizon configuration is likely the culprit. Check for:

• Mismatched zone files between internal/external DNS
• Incorrect view definitions based on source networks
• Conflicting records between zones

Create a table mapping internal resources to their expected DNS responses for both internal and external queries. Then systematically test each one to identify discrepancies.

Implementing Robust DNS Architecture

A. Designing redundant DNS infrastructure

DNS failures can bring your entire network to its knees. Nobody wants that headache.

In Meraki networks, you’ll want at least two primary DNS servers and two secondary servers. Spread these across different geographic locations and ISPs if possible.

Consider this setup:

• Primary DNS: Meraki’s built-in DNS + Cloud DNS provider
• Secondary DNS: On-premises DNS server + Different cloud provider

This way, if one provider goes down, you’re still covered. Smart, right?

Don’t just rely on your ISP’s DNS servers either. They’re usually the first to get overloaded during major outages. Instead, mix public DNS providers like Cloudflare (1.1.1.1) and Google (8.8.8.8) with your private DNS infrastructure.

B. Optimizing DNS query paths

The path your DNS queries take matters big time.

Configure your Meraki MX to send queries to the closest DNS server first. This cuts down on those annoying resolution delays that drive users crazy.

Implement DNS forwarding rules in your Meraki dashboard to direct specific domain queries to specialized DNS servers. For example, send internal domain lookups to your local DNS server while external ones go to public resolvers.

And please, cache those DNS results! Set appropriate TTL (Time-to-Live) values to balance freshness with performance.

C. Monitoring DNS performance metrics

You can’t fix what you don’t measure. With Meraki, set up alerts for:

• DNS response times over 100ms
• Failed DNS queries exceeding 5% of total
• Sudden spikes in DNS traffic (possible attack)

Tools like PRTG or SolarWinds can provide deeper DNS analytics than what’s available in the Meraki dashboard. They’re worth the investment.

Create a DNS performance dashboard that shows query volumes, response times, and failure rates at a glance.

D. Creating DNS failure recovery procedures

When DNS goes down, every second counts.

Document these recovery steps for your team:

1. Identify which DNS servers are failing (Meraki logs will show this)
2. Switch client DNS settings via DHCP if primary servers are down
3. Clear DNS caches on affected devices
4. Temporarily hardcode critical hostnames in local host files for emergency access

Run quarterly DNS failure drills. Seriously. Pull the plug on your primary DNS and see if your redundancy actually works. Most teams find surprising gaps when they actually test this.