Bug 58568

Summary:	glibc does not exactly follow nsswitch.conf settings
Product:	[Retired] Red Hat Linux	Reporter:	Eugene Kanter <ekanter>
Component:	glibc	Assignee:	Jakub Jelinek <jakub>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Brian Brock <bbrock>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	7.2	CC:	fweimer, leon
Target Milestone:	---
Target Release:	---
Hardware:	i386
OS:	Linux
Whiteboard:
Fixed In Version:	2.3.2-27.9	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2003-04-22 02:47:16 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Eugene Kanter 2002-01-20 00:37:38 UTC

Description of Problem:

DNS requests made ahead of NIS requests despite the settings in nsswitch.conf.

Version-Release number of selected component (if applicable):glibc-2.2.4-13


How Reproducible:

always

Steps to Reproduce:
1. configure 7.2 as NIS client, check default nsswitch.conf settings: hosts: ..
nis dns. NIS comes first.
2. make sure that NIS hosts map contains some names. For example include following:

glibcnisbug  127.0.0.1

3. start "tcpdump port 53" on one terminal and "ping glibcnisbug" on another
terminal.

Actual Results:

tcpdump shows DNS requests made to the default DNS server asking for an IP
address of glibcnisbug.defaultdomain.com, where defaultdomain is "search" from
/etc/resolv.conf

Expected Results:

No DNS requests made, because NIS request must be made first.

Additional Information:
	
This bug was found when DNS server went offline thus causing a huge delay in
name resolution. Investigation revealed that DNS requests were made before NIS
despite settings in nsswitch.conf

Comment 1 hjl 2002-07-16 22:20:06 UTC

I have similar problem when the name servers
for lucon.org were off-line. Even though I put

x.x.x.x ocean.lucon.org lucon.org

in /etc/hosts and there is

hosts:      files nisplus nis dns

in /etc/nsswitch.conf,

# ssh lucon.org

took a long time to resolve since it
tried DNS first. I tracked it down
to the way how getaddrinfo works. But I never
found time to fix it since my name server
is working now.

Comment 2 Chris Ricker 2003-01-07 05:51:55 UTC

See also

Bug 71546: ldap for user files always used, regardless of nsswitch.conf
Bug 66682: nis for user files always used, regardless of nsswitch.conf
Bug 63631: local users never authenticated if ldap server down

Comment 3 Landon Curt Noll 2003-02-22 15:20:26 UTC

It appears that this nsswitch.conf order problem has been resolved in rawhide.
See:

    https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=84105#c6

for details.

Comment 4 Landon Curt Noll 2003-02-25 19:26:48 UTC

A clarification on: 
 
    https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=84105#c6 
 
You should NOT install those RPMs on a production system.  Rawhide 
is raw bits.  Those RPMs were only in relationship to various DNS 
issues.  Those rpms have a number of non-DNS related problems. 
For example, they cause the rpm command to dump core.  They did, 
however,  resolve the DNS issues, with the possible exception of 
excessive IPv6 lookups.

Comment 5 Ulrich Drepper 2003-04-22 02:47:16 UTC

Now there are RPMs which you can use on production systems.  RHL9 should handle
this well.  I've fixed a few more problem especially related to nscd and ldsp
which will be in the next binary.  Closing the bug now.