Usage: DnsCmd /OfflineSign /DeleteKey /Cert /FriendlyName /Subject /Issuer /Serial - friendly name of the certificate - subject ...

Usage: 
 DnsCmd /OfflineSign /DeleteKey /Cert [/FriendlyName ]
 [/Subject ] [/Issuer ] [/Serial ]

    -- friendly name of the certificate
         -- subject of the certificate, for example,
                     "CN = example.com 43576 RSASHA1 257". It is case
                     sensitive.
          -- issuer of the certificate.
    -- serial number of the certificate as a string of 2-digit
                     hex, for example,
                     "79 7f 1e 1b 41 20 cf 8d 4a 9a 55 b7 83 c8 33 e9"
  One or more of the above options can be given. The options must
  identify one unique certificate in the MS-DNSSEC machine certificate store.