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1. IL-0502 The JupyterHub at temple.2i2c.cloud stopped resolving in DNS after a wildcard record was added for a new cluster

   2i2c2025

   Symptoms

   On 20 August 2025 at 10:02 AM Pacific time, an automated uptime check on temple.2i2c.cloud started failing and paged 2i2c: the JupyterHub at temple.2i2c.cloud could not be reached, shortly before the community that uses it was to give a demo.

   DNS resolution failuresService outage

   Trigger

   At 9:21 AM, while setting up a new cluster for Temple, a wildcard DNS record *.temple.2i2c.cloud was added pointing to the new cluster's Ingress IP.

   Root cause

   Configuration change

   Component

   Authoritative DNS servers and records

   Contributing factor

   Unverified assumptionCache-masked failureUnreviewed defaults

   Detection

   Automated uptime alerts caught the failure at 10:02 AM, before the community reported it in a support ticket at 10:09 AM.

   Remediation

   • Added an explicit A record for temple.2i2c.cloud in Namecheap
   • Lowered the DNS TTL from the 30-minute default to 5 minutes
   • Offered the community member running the demo an /etc/hosts entry as a workaround

   Action items

   • Give everyone on the team access to Namecheap, or move to another DNS provider
   • Use a 5-minute TTL instead of 30 minutes for all new DNS entries
   • Document that adding a *.X.2i2c.cloud DNS entry requires adding an X.2i2c.cloud entry as well

   Lessons

   Adding a wildcard record for a subdomain stopped a broader wildcard from answering for that subdomain's own name, so a *.X.2i2c.cloud record needs an X.2i2c.cloud record alongside it. The 30-minute default TTL at Namecheap meant any DNS fix could take that long to propagate, and the engineer creating the original record had no access to the DNS provider.

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