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    Customer access to OPAC: Unknown Host / DNS address could not be found


    • Product: Aleph
    • Product Version: 20, 21, 22, 23
    • Relevant for Installation Type: Dedicated-Direct, Direct, Local, Total Care



    On an Ex Libris dc04 hosted server, where the Load Balancer (LB) is being used, though Ex Libris staff -- from inside the EL network -- are able to access a customer OPAC at, the customer cannot.  

    If the "CNAME" (described below) is used to access the OPAC, the customer may get the initial screen but get the following errors when trying to do a search:  "This site can’t be reached.’s server DNS address could not be found." 


    This "...alph.dc04..." address is an internal hostname which does not work for access from outside the EL network.  The customer needs to use the CNAME, such as,, or the public IP address.  

    Note:  This CNAME must appear as the 

      $alephe_root/aleph_start     setenv WWW_HOST
      $alephe_root/www_server.conf setenv server_httpd
      $alephe_root/www_server.conf setenv server_httpsd
      ./apache/htdocs/.index.html “var loc”.

    The internal hostname cannot be used for these if the customer is to be able to access the OPAC.

    (When the CNAME is not used in the above files, though the customer will get the initial OPAC screen via the CNAME, they will get the error shown above when trying to do a search.)   



    • Article last edited: 6-Jun-2016