- Lab
- A Cloud Guru
Troubleshooting DNS
In this hands-on lab, we will walk though troubleshooting DNS resolution issues on the provided host.
Path Info
Table of Contents
-
Challenge
Verify the Issue and Check `/etc/nsswitch.conf`
We'll first need to verify that the issue exists by attempting the
curl
the header ofacloudguru.com
:curl -I https://acloudguru.com/
Then we need to verify that nothing is missing in this file, and we should pay attention to the ordering of the
hosts
value:hosts: files dns myhostname
-
Challenge
Verify `/etc/hosts` Contents
We'll want to make sure there aren't any entries in this file that would cause issues:
cat /etc/hosts
-
Challenge
Determine If the DNS Host is Listening on TCP Port 53
If the host is listening on TCP port 53, we'll know by running this:
telnet 10.0.1.1 53
-
Challenge
Check Resolution Using the 10.0.0.2 DNS Host
Now that we've verified that the host listed in
/etc/resolv.conf
isn't available on TCP port 53, check if resolution is working on the DNS host10.0.0.2
:dig @10.0.0.2 acloudguru.com
-
Challenge
Change the Configuration to Use the 10.0.0.2 Host
We can do this with network manager, or by editing
/etc/resolv.conf
. If we restart networking, this is the IP that will be used via DHCP. Remove the10.0.1.1
entry.
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