Failure of Keio DNS Caching Servers (Oct 13)

(Last updated: October 13, 2026, 6:55p.m.)

An issue occurred with the Keio DNS caching servers as described below, but it has now been resolved.

• Date/Time: Tuesday, October 13, 2026, approximately from 4:30p.m. to 5:45p.m.
• Target: Keio Official DNS Caching Servers
  
  • 131.113.1.1 (kogwy.cc.keio.ac.jp)
  • 131.113.1.8 (ns.st.keio.ac.jp)
  • 131.113.191.8 (ns.sc.keio.ac.jp)
  • 131.113.192.8 (ns.mita.keio.ac.jp)
  • 131.113.224.8 (ns.hc.keio.ac.jp)
• Impact: Inability to resolve domain names on clients configured to use the above DNS caching servers
• Cause: System fault on the DNS caching servers
• Remarks: Clients referencing DNS caching servers other than those listed above (such as keiomobile2, eduroam, and ADST administrative systems) were not affected

We sincerely apologize for any inconvenience caused.