While an application is working, the network connection is terminated.
Then, even though the network connection recover from its termination.
the InetAddress.getByName() can not get the IP address and outputs "UnKnownHostException"

Expectation is that the getByName() can get IP address after the network connection's recovery.


1. Reproducing

 1) Modify 2 lines of the attached sample code.

    Please specify host name of each which are connectted to the network.
  
    ex.
      String hostA = "srv1";
      String hostB = "srv2";

 2) Compile the source code
 3) Invoke "Java InetAddressTP"
    -> You will see the following message.
   
** 1st resolution must be resolved **
srv1/111.222.33.44
** Thread will sleep, disable network by detaching the network cable **

 4) Disable the network connection
    ex.
      by pulling out LAN connector

 5) Wait about 20 seconds, you will see the following.

java.net.UnknownHostException: srv2
        at java.net.InetAddress.getAllByName0(InetAddress.java:948)
        at java.net.InetAddress.getAllByName0(InetAddress.java:918)
        at java.net.InetAddress.getAllByName(InetAddress.java:912)
        at java.net.InetAddress.getByName(InetAddress.java:832)
        at InetAddressTP.main(InetAddressTP.java:36)
** Thread will sleep, enable network by connecting the network cable **

  6) Enable the netwrok connection
      ex.
        by inserting LAN connector
 
  7) You will see the following message

** 3rd resolution, must be resolved **
java.net.UnknownHostException: srv2
        at java.net.InetAddress.getAllByName0(InetAddress.java:953)
        at java.net.InetAddress.getAllByName0(InetAddress.java:918)
        at java.net.InetAddress.getAllByName(InetAddress.java:912)
        at java.net.InetAddress.getByName(InetAddress.java:832)
        at InetAddressTP.main(InetAddressTP.java:56)

  Here, we expect the following message shows up because the network connection
  is recovered and alive,

** 3rd resolution, must be resolved **
srv2/111.222.33.55

but the above exception appears.


2. Configration
  
 MPU : Pentium IV 1.4 [GHz]
 Mem : 384 [MB]
 OS : Windows2000 (SP2, Japanese)
 JDK : 1.4.1-beta-b13, 1.4.0fcs, 1.3.1_03


3. Note

 - Please imagine the case that network connection is terminated and
   recover automatically.
   Besides, your application runs like server process and try to connect
   some nodes periodically.
   If your application is running on a server, you expect the application
   can reconnect automatically when the network connection recovers ?

   However, according to the above-mentioned behavior,
   once the network connection is terminated, the application
   can not reconnect later on automatically even if it recovers.

   That looks big problem for the application on a server.


2002-05-29
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