Updated the "How to prevent processing requests with undefined server names" example to use the "server_name" directive with an empty string argument to match requests without the "Host:" request header line.

<!ELEMENT  digest       (title, article+) >

<!ELEMENT  article      (para+) >
<!ATTLIST  article      date CDATA #REQUIRED >

<!ENTITY % content      SYSTEM  "content.dtd" >
          %content;