Unable to Access External Websites On-Campus


I can access a website on an off-campus network, but when I attempt to access this website on the on-campus network I get the following error:

Server not found.


Security message: Access Blocked.


There can be multiple causes for this issue. The computer DNS cache could have outdated information. The IP information could have been recently updated and the TTL (Time To Live) has not expired on the campus DNS servers. The changes could have not been updated by the authoritative DNS servers (web host owned).


  1. Clear the devices DNS cache
  2. If changes were recently made, the client should contact their webhosting service to identify the TTL (Time To Live) value assigned. The authoritative DNS server of the domain sets this value. The typical value is between 86400 and 162800 (24 - 48 hours). This is how long it will take for a change to spread through the internet.
  3. The client should verify with the web hosting service that the DNS changes have been completed.
    • If the client knows the IP the hostname should resolve to, at a command prompt enter "nslookup domain.com" replacing domain.com with the domain in question.
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Article ID: 672
Tue 9/23/14 1:42 PM
Wed 7/15/20 9:01 AM