Cisco Cyber Vision New UI Administration Guide, Release 5.6.0

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Cisco Cyber Vision New UI Administration Guide, Release 5.6.0

DNS resolution issues

Updated: September 8, 2026

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Describes DNS resolution issues, which are network connectivity problems that prevent devices from converting domain names into IP addresses, often resulting in failures to communicate with external services.

DNS resolution issues are network connectivity problems that prevent a device from converting domain names, such as us.ciscoiot.com , into IP addresses.

  • They often lead to failures in communication with external endpoints or authentication services.

  • They manifest through observable error messages, repeated application restarts, or timeouts when accessing network resources.

DNS resolution and network problems symptoms

The following symptoms may indicate DNS or general network connectivity issues.

  • Error obtaining an authentication token, such as: 
    Get "https://us.ciscoiot.com/sramgmt/auth/token": dial tcp: lookup us.ciscoiot.com on 8.8.1.1:53: i/o timeout

  • The application restarts frequently.

  • Log messages including:

    • WRN ProxyUrl env variable isn't set
    • Successful JWT token generation, but failure occurs during token request.
    • DNS query timeout on server 8.8.1.1

Root causes of DNS and network connectivity issues

This topic describes the typical causes of DNS and network connectivity issues.

  • The device cannot resolve domain names (such as us.ciscoiot.com ) using the configured DNS server (for example, 8.8.1.1).

  • Firewall or network restrictions are blocking DNS requests (UDP on port 53).

  • The device cannot reach external internet endpoints due to connectivity issues.

  • Network misconfigurations, such as incorrect MTU settings, default gateway, or routing tables.

Fix DNS resolution issues

Confirm that your device can resolve domain names and, if necessary, configure it to use a working DNS server.

DNS resolution failures can prevent applications from contacting required services. These steps help you diagnose and correct DNS configuration issues.

Before you begin

Follow these steps to check and correct DNS resolution:

Procedure

  1. Test domain name resolution from your device:

    Example:

    nslookup us.ciscoiot.com 8.8.8.8
nslookup us.ciscoiot.com 8.8.1.1

  2. If the DNS queries fail, configure your system to use a reachable DNS server:

    Example:

    echo "nameserver 8.8.8.8" >> /etc/resolv.conf

  3. Confirm the device’s default gateway and routing table are correct.

  4. Check if you can reach the cluster URL:

    Example:

    ping us.ciscoiot.com
curl -v https://us.ciscoiot.com/sramgmt/auth/token

The device should now be able to resolve us.ciscoiot.com and similar domains using the updated DNS server.