Bug 1462505 - systemd-resolved falls back to google public DNS servers
systemd-resolved falls back to google public DNS servers
Status: NEW
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: systemd (Show other bugs)
All Linux
unspecified Severity medium
: rc
: ---
Assigned To: systemd-maint
Depends On:
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Reported: 2017-06-18 04:07 EDT by Ahmed Nazmy
Modified: 2018-02-21 10:48 EST (History)
4 users (show)

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Tracker ID Priority Status Summary Last Updated
Red Hat Knowledge Base (Solution) 3083631 None None None 2017-06-18 06:33 EDT

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Description Ahmed Nazmy 2017-06-18 04:07:09 EDT
Description of problem:

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

How reproducible:

Steps to Reproduce:
1. Remove namserserver from /etc/resolv.conf
2. Remove DNS settings from /etc/sysconfig/network-scripts/ifcfg-*
3. systemctl restart systemd-resolved
4. Enable systemd-resolved in /etc/nsswitch.conf:  "hosts: files dns resolve"
5. Perform any task that requires name resolution .

Actual results:
the logs shows clearly the query is directed to google DNS server :
Jun 18 08:01:52 rhel7 systemd: Started Network Name Resolution.
Jun 18 08:01:56 rhel7 systemd-resolved: Switching to system DNS server

tcpdump confirms it :

08:01:56.600174 IP google-public-dns-a.google.com.domain > rhel7.example.com.60568: 50314 1/0/0 A (44)
08:01:56.750680 IP rhel7.example.com.60568 > google-public-dns-a.google.com.domain: 2601+ PTR? (46)
08:01:56.778265 IP google-public-dns-a.google.com.domain > rhel7.example.com.60568: 2601 1/0/0 PTR redirect.redhat.com. (79)

Expected results:
systemd-resolved doesn't use fallback nameservers and reports an error instead

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