Objective
Diagnose and resolve DNS issues affecting VoIP performance.
Applies To
- 8x8 Network Utility Tool
- DNS
Procedure
Understanding DNS Testing
DNS (Domain Name System) helps direct your internet traffic to the correct servers. Geo-routing ensures that your connection is routed to the closest and most efficient Data Centre based on your location using 8x8 GTM (Global Traffic Manager) DNS.
Identifying Geo-Routing Issues
When reviewing your DNS test results in the Network Utility tool, watch for this error message: “*** Conflicting DNS resolutions: Two or more DNS Servers are in disagreement over."
This means that different DNS servers are routing your connection to different regions. For example, your local DNS might route your traffic to a server in India, while 8x8 GTM routes it to a server in the USA. This mismatch can cause call delays, poor audio quality, or dropped calls.
Steps to Resolve Local Network DNS Issues
Confirm Geo-Routing Discrepancy
- Run a DNS test using the Network Utility tool.
- Check the results for mismatched region assignments.
- Identify whether the conflict is caused by Local DNS Server 1, Local DNS Server 2, or both.
Modify DNS Settings for Optimal VoIP Performance
1. Use ISP-Recommended DNS Settings
For the best performance, always use the DNS servers provided by your ISP. If VoIP issues persist, try one of the alternative DNS servers listed below:
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2. Using 8x8 GTM DNS Servers (For Device or Dedicated VLAN Only)
If necessary, configure 8x8 GTM DNS only for voice devices or dedicated VoIP VLANs:
- 8x8 GTM Primary DNS: 8.28.0.9
- 8x8 GTM Secondary DNS: 192.84.18.11
⚠️ Important: Do not set 8x8 GTM DNS as the primary DNS for your entire LAN, as it may cause internet connectivity issues for non-VoIP devices.
3. Avoid Anycast DNS for VoIP
Anycast DNS may route traffic to servers in the wrong geographic location, affecting call quality.
4. How to Update DNS Settings
- Router: Update the DNS settings in your router’s network settings (varies by make/model).
- Conditional Forwarding: If supported, apply DNS conditional forwarding to route VoIP traffic correctly.
- PCs & Handsets: If issues persist, manually configure DNS settings on individual devices.
5. Configure DNS on VoIP Devices
If VoIP issues remain after changing network DNS, set VoIP handsets to use 8x8 GTM DNS directly.
- Poly Devices – Update DNS in network settings. See Set a Static IP on a Poly Phone.
- Yealink Devices – Configure DNS manually in handset settings. See Setting a Static IP and DNS on Yealink Phones in the Web GUI.
Additional Information
Use Continuous Testing as a Diagnostic Tool
Continuous network monitoring and testing are essential to proactively detect and resolve DNS-related issues. The following tools can help analyze network performance and identify VoIP-related DNS problems:
1. Packet Analysis & Network Tracing
- Ping Plotter – Visual traceroute tool for detecting latency and packet loss.
- WinMTR / MTR (My Traceroute) – Combines ping and traceroute for continuous network testing.
- Wireshark – Deep packet analysis to identify DNS resolution issues.
2. Network Monitoring Solutions
- SolarWinds Network Performance Monitor (NPM) – Enterprise-grade network monitoring.
- PRTG Network Monitor – Comprehensive network performance tracking.
- Nagios – Open-source network monitoring with alerting capabilities.
- Zabbix – Real-time network monitoring for DNS and VoIP traffic.
- NetFlow Analyzer (ManageEngine) – Traffic analysis for detecting DNS anomalies.
3. Internet & Security Monitoring
- Pingdom – Website and network monitoring to detect connectivity issues.
- Bitdefender Box – Monitors home and business networks for security threats.
4. Bandwidth & Latency Testing
- iPerf3 – Measures network bandwidth and performance for VoIP traffic.
By following these steps, you can effectively diagnose and resolve DNS-related issues, ensuring optimal performance for 8x8 services.