TCP/IP startup problems

TCP/IP startup problems are common sources of unsuccessful DDF operation.

• The TCP/IP listener is not started because of a TCP/IP configuration problem, or because the DNS is not available during DDF startup.

  In this situation, DDF startup completes, but the domain name in message DSNL004I is -UNKNOWN. Connections cannot be established until the TCP/IP listener is successfully established and TCP/IP services become available for DDF. After the initial connection failure, Db2 periodically attempts to reinitialize TCP/IP. When the connection is successful, Db2 issues message DSNL519I.

• A TCP/IP getaddrinfo socket call fails during DDF startup.

  When this failure occurs, Db2 issues the following message:

  DSNL512I ? DSNLILNR TCP/IP GETADDRINFO(myhostname) FAILED WITH
             RETURN CODE=1 AND REASON CODE=78AE1004
  

  Possible causes:

  • The DDF application cannot access the TCPDATA data set.
  • The DNS is not available.
  • There is no entry for the IP address of the local host in the DNS.
  • There is no entry in the /etc/hosts file.
  • There is no entry in the hlq.HOSTS.ADDRINFO data set.

  The following search order is used to find the TCPDATA data set for the DDF application:

  1. /etc/resolv.conf file
  2. Data sets in the //SYSTCPD DD statement
  3. jobname.TCPIP.DATA
  4. SYS1.TCPPARMS(TCPDATA)
  5. TCPIP.TCPIP.DATA

  The first file in this list is used as the TCPDATA file. After this file is correctly defined to DDF, you can use the TRACE RESOLVER statement in this file to further diagnose a problem. The resolver trace displays the IP address that is being resolved, so you can confirm that the gethostid call was successful. The resolver trace also displays any errors that are encountered with the DNS or local files. The output of the resolver trace is in the JES log of the DDF started task, DSNDIST.