Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Bug 837695

Summary: glibc sends spurious DNS requests for certain hostnames
Product: Red Hat Enterprise Linux 6 Reporter: Jeroen van Bemmel <jvb127>
Component: glibcAssignee: Patsy Griffin <pfrankli>
Status: CLOSED ERRATA QA Contact: qe-baseos-tools-bugs
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 6.5CC: fweimer, law, mcermak, mfranc, rfreire
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Cause: A buffer in glibc's resolver code was too small to handle results for certain DNS queries. Consequence: As a result, the query would have to be repeated after a larger buffer was allocated. This wastes time and network bandwidth. Fix: The buffer has been enlarged to handle the larger DNS results. Result: No extraneous DNS queries are generated.
 Story Points: ---
Clone Of:
: 1003669 (view as bug list) Environment:
Last Closed: 2013-02-21 07:05:13 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1003669    
Attachments:
Description Flags
Potential fix none

Description Jeroen van Bemmel 2012-07-04 21:05:40 UTC 
Description of problem:
A call to getaddrinfo() using glibc x86_64 results in duplicate DNS queries for the same A-record, causing redundant network traffic and extra delay for the client application. It may also break certain DNS-based load balancing schemes

Version-Release number of selected component (if applicable):
glibc latest HEAD

How reproducible: Always

Steps to Reproduce:
1. Start tcpdump using "udp port 53"
2. wget -4 www.google.com
  
Actual results:
2 DNS A queries + 2 identical answers for "www.google.com"

Expected results:
Single DNS A query + answer

Additional info:
See glibc bug report: http://sourceware.org/bugzilla/show_bug.cgi?id=14307
Comment 2 Jeff Law 2012-07-05 15:41:19 UTC 
*** Bug 837696 has been marked as a duplicate of this bug. ***
Comment 3 Jeff Law 2012-07-05 15:41:57 UTC 
*** Bug 837697 has been marked as a duplicate of this bug. ***
Comment 4 Jeff Law 2012-07-05 15:42:41 UTC 
*** Bug 837698 has been marked as a duplicate of this bug. ***
Comment 5 Jeff Law 2012-07-05 21:03:40 UTC 
Created attachment 596504 [details]
Potential fix
Comment 6 Jeroen van Bemmel 2012-07-06 01:24:16 UTC 
Comment on attachment 596504 [details]
Potential fix

A slightly different patch was submitted to the libc-alpha mailing list: http://sourceware.org/ml/libc-alpha/2012-07/msg00057.html

It will probably be committed into SVN tomorrow (Friday)
Comment 7 Jeff Law 2012-07-06 02:29:46 UTC 
I'm aware of that change; the RHEL 6 codebase is slightly different and in fact doesn't have the codepath where the fix is being made upstream.
Comment 10 Jeff Law 2012-09-05 18:51:10 UTC 
*** Bug 854759 has been marked as a duplicate of this bug. ***
Comment 12 errata-xmlrpc 2013-02-21 07:05:13 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2013-0279.html