IC86912: DATAPOWER DOES NOT USE THE TTL VALUE PASSED IN THE DNS CNAME RECORD.

APAR status

• Closed as program error.

Error description

• Datapower only uses the Time To Live (TTL) value in the DNS A
  Record. The appliance
  should also consider the TTL value passed in the CNAME
  field, and use this value if it is shorter than the TTL value of
  the A Record
  

Local fix

Problem summary

• Affected are customers using the Datapower appliance to
  reference other network devices via DNS aliases in an
  environment where these DNS aliases might change.
  
  When resolving a DNS alias name where the timeout associated
  with the alias to a canonical name is shorter than the one
  associated with the canonical name's IP address, Datapower was
  failing to re-resolve the alias name immediately after its DNS
  record had expired.
  
  Datapower DNS resolution component honors only the TTL value
  returned in A or AAAA DNS records, failing to account for
  the TTL
  value in CNAME records. Therefore, if a network alias name were
  resolved via a pair of DNS records, e.g. of CNAME and A types,
  and the TTL value of CNAME record were shorter than the one of
  the
  A record, Datapower would cache the name-to-address translation
  entry using the A TTL, effectively disregarding the CNAME TTL
  value, which is not compliant with RFC-1034.
  

Problem conclusion

• The fix sets TTL to the lesser of the A record or the CNAME
  record.
  
  The fix is available in 3.8.2.16, 4.0.1.14, 4.0.2.10 and 5.0.0.4
  
  For a list of the latest fix packs available, please see:
  http://www-01.ibm.com/support/docview.wss?uid=swg21237631
  

Temporary fix

• Customers that have control over their DNS infrastructure can
  configure the server to use timeout values on their A or AAAA
  records to be shorter than the ones for CNAME records.
  

Comments

APAR Information

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

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

Fix information

• Fixed component name

  DATAPOWER

• Fixed component ID

  DP1234567

Applicable component levels

• R382 PSN

     UP

• R401 PSN

     UP

• R402 PSN

     UP

• R500 PSN

     UP