PH58715: Implement a cache expiry (TTL) for DNS caching for outbound connections.

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• Prior to CICS TS 6.1 every time a URIMAP was used for an
  outbound web request, a DNS lookup was done. From CICS TS
  6.1onwards the DNS entry is cached until a connection fails.
  If a connection using a cached IP address fails, a new DNS
  lookup is done and the cache updated. Otherwise, a disable and
  re-enable of the URIMAP is required to make CICS perform a new
  DNS lookup.
  

Local fix

• DISABLE / ENABLE one URIMAP per host.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS TS users                            *
  ****************************************************************
  * PROBLEM DESCRIPTION: DNS cache is not automatically expired  *
  *                      so any DNS changes are not detected     *
  *                      and require manual intervention.        *
  ****************************************************************
  Workload is spread over two sites (A and B).  For system
  maintenance , all workload is switched from site A to site B by
  updating the DNS entries. When work on Site A is completed, it's
  made available for work (ie put back online) and DNS updated.
  However site B is not taken offline as it runs production work.
  
  The CICS cache is not updated with this DNS update.  So work
  continues to flow to site B incorrectly.  To solve the problem
  manual intervention is required by the operator.
  

Problem conclusion

• CICS is changed to expire the cache every 60 seconds.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UI97657 UI97658

Modules/Macros

• DFHWBA   DFHWBAP  DFHWBAPF DFHWBDUF DFHWBRP  DFHWBSC  DFHWBSR
  DFHWBUR  DFHWBXM  DFHWBXN
  

Fix information

• Fixed component name

  CICS TS Z/OS V6

• Fixed component ID

  5655YA100

Applicable component levels

• R400 PSY UI97658

     UP24/07/18 P F407  

• R500 PSY UI97657

     UP24/07/25 P F407  

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.