Registering a server fails with "UnknownHostException"

Example error message in security_provisioning.log 

Got exception while connecting to 
  server lmrk10.lpc.lawson.com on port 9201
Stack Trace :
com.lawson.security.server.LawsonNetException: Got exception while connecting to server 
  lmrk10.lpc.lawson.com on port 9201
at com.lawson.security.server.Connection.<init>(Connection.java:89)
at com.lawson.security.server.LASecurityConnection.<init>
  (LASecurityConnection.java:18)
at com.lawson.security.server.ConnectionUtil.getConnectionToArbitrarySecurityServer
  (ConnectionUtil.java:314)
at com.lawson.security.authen.ServerFederationManagerRemoteImpl.pingServer
  (ServerFederationManagerRemoteImpl.java:234)
at com.lawson.security.server.events.ServerServerFederationEvent.pingServer
  (ServerServerFederationEvent.java:918)
at com.lawson.security.server.events.ServerServerFederationEvent.processRegisterServer
  (ServerServerFederationEvent.java:713)
at com.lawson.security.server.events.ServerServerFederationEvent.process
  (ServerServerFederationEvent.java:110)
at com.lawson.lawsec.server.SecurityEventHandler.processEvent
  (SecurityEventHandler.java:550)
at com.lawson.lawsec.server.SecurityEventHandler.run(SecurityEventHandler.java:347)
Caused by: java.net.UnknownHostException: lmrk10.lpc.lawson.com
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:850)
at java.net.InetAddress.getAddressFromNameService(InetAddress.java:1201)
at java.net.InetAddress.getAllByName0(InetAddress.java:1154)
at java.net.InetAddress.getAllByName(InetAddress.java:1084)
at java.net.InetAddress.getAllByName(InetAddress.java:1020)
at java.net.InetAddress.getByName(InetAddress.java:970)
at com.lawson.security.server.Connection.<init>(Connection.java:50)
... 8 more 
Wed Feb 13 17:50:25 CST 2013 - 332950131: Failed to register [LMRK10.LPC.LAWSON.COM;9201
  ;9209;LANDMARK] with [LSF901.SKYNET.LAWSON.COM;11001;11002;LSS]
Wed Feb 13 17:50:25 CST 2013 - 332950131: Cannot reach the specified server 
 [LMRK10.LPC.LAWSON.COM;9201;9209;LANDMARK]. It will not be registered. Check to make 
  sure you have the correct server information.

To resolve this issue:

  1. Verify that you are using the correct host and ports to register the Landmark server.

    The host and ports must be the same as those defined in the Landmark lsservice.properties file.

  2. Verify that the security server is running on Landmark and is listening to the default and SSL ports defined in the lsservice.properties file.

    Example:

    netstat anlgrep 9207

    netstat anlgrep 9208

  3. Verify that both the LSF and Landmark servers can access each other.

    From the Landmark server, ping the LSF server and from the LSF server, ping the Landmark server.