When troubleshooting name resolution issues in Linux, /etc/hosts entries take precedence over DNS lookups. The workstation's /etc/hosts file contains the line:
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104.18.99.101 www.comptia.org
This means any attempt to access www.comptia.org will resolve to 104.18.99.101, regardless of the real DNS response. However, both dig and nslookup show the correct IP as 104.18.16.29.
Because the local /etc/hosts entry overrides DNS, and the hardcoded IP is either incorrect or unreachable, all network traffic to www.comptia.org will fail or not reach the intended destination, resulting in the observed connectivity issue (Destination Host Unreachable).