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TASK_9-DNS_Troubleshooting.sh
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TASK_9-DNS_Troubleshooting.sh
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TASK 9 - DNS Troubleshooting - 2020-07-07 || 03:20 AM
REQUIREMENT:
The system admins team of xFusionCorp Industries has noticed intermittent issues with DNS resolution in several apps . App Server 3 in Stratos Datacenter is having some DNS resolution issues, so we want to add some additional DNS nameservers on this server.
As a temporary fix we have decided to go with Google public DNS. Please make appropriate changes on this server.
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CONTENT:
I. REFERENCES
II. STEPS - SUMMARY
III. STEPS - BREAKDOWN
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I. REFERENCES
https://community.kodekloud.com/t/taks-dns-troubleshooting/1485
https://community.kodekloud.com/t/dns-troubleshooting/2955
https://support.rackspace.com/how-to/changing-dns-settings-on-linux/
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II. STEPS - SUMMARY
1. Connect via SSH to the correct app server.
2. Verify if DNS is really not working by doing a ping test.
3. Edit /etc/resolv.conf and add nameserver for Google
4. Test connectivity
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III. STEPS - BREAKDOWN
# This was actually quite an easy one. Wish I could have started this earlier.
# I was a bit disoriented or I guess distracted the whole day that I only started working on this lab
# 8 hours after it was assigned to me, adnd I only worked on this lab for 15 mins or less!
# Anyway, this lab just requires to add a DNS name server to the App server.
# 1. Connect via SSH to the correct app server
thor@jump_host /$ sshpass -p '******' ssh -o StrictHostKeyChecking=no tony@172.16.238.10
Warning: Permanently added '172.16.238.10' (ECDSA) to the list of known hosts.
[tony@stapp01 ~]$
# 2. Verify if DNS is really not working by doing a ping test.
[tony@stapp01 ~]$ ping www.google.com
PING www.google.com (216.58.206.4) 56(84) bytes of data. # Well this seems to
64 bytes from fra16s20-in-f4.1e100.net (216.58.206.4): icmp_seq=1 ttl=118 time=5.08 ms # be working...
64 bytes from fra16s20-in-f4.1e100.net (216.58.206.4): icmp_seq=2 ttl=118 time=5.42 ms
64 bytes from fra16s20-in-f4.1e100.net (216.58.206.4): icmp_seq=3 ttl=118 time=5.17 ms
64 bytes from fra16s20-in-f4.1e100.net (216.58.206.4): icmp_seq=4 ttl=118 time=5.12 ms
64 bytes from fra16s20-in-f4.1e100.net (216.58.206.4): icmp_seq=5 ttl=118 time=5.11 ms
64 bytes from fra16s20-in-f4.1e100.net (216.58.206.4): icmp_seq=6 ttl=118 time=5.16 ms
^C
--- www.google.com ping statistics ---
6 packets transmitted, 6 received, 0% packet loss, time 5008msrtt min/avg/max/mdev = 5.087/5.180/5.421/0.145 ms
[tony@stapp01 ~]$
[tony@stapp01 ~]$
# 3. Edit /etc/resolv.conf and add nameserver for Google
[tony@stapp01 ~]$ sudo ls -l /etc/resolv.conf
We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:
#1) Respect the privacy of others.
#2) Think before you type.
#3) With great power comes great responsibility.
[sudo] password for tony:
-rw-r--r-- 1 root root 69 Jul 6 19:00 /etc/resolv.conf
[tony@stapp01 ~]$ # So apparently 'nano'
[tony@stapp01 ~]$ sudo nano /etc/resolv.conf # isn't really supported
sudo: nano: command not found # in KodeKloud labs.
[tony@stapp01 ~]$
[tony@stapp01 ~]$ sudo vi /etc/resolv.conf # Add nameserver
[tony@stapp01 ~]$
[tony@stapp01 ~]$ sudo cat /etc/resolv.conf
search stratos.xfusioncorp.com
nameserver 127.0.0.11
nameserver 8.8.8.8 # added nameserver 8.8.8.8
nameserver 8.8.4.4 # added nameserver 8.8.4.4
options ndots:0
[tony@stapp01 ~]$
# 4. Test connectivity
[tony@stapp01 ~]$ ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=118 time=5.75 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=118 time=5.08 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=118 time=5.10 ms
^C
--- 8.8.8.8 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 5.080/5.311/5.754/0.318 ms
[tony@stapp01 ~]$
[tony@stapp01 ~]$ ping 8.8.4.4
PING 8.8.4.4 (8.8.4.4) 56(84) bytes of data.
64 bytes from 8.8.4.4: icmp_seq=1 ttl=118 time=5.30 ms
64 bytes from 8.8.4.4: icmp_seq=2 ttl=118 time=5.64 ms
64 bytes from 8.8.4.4: icmp_seq=3 ttl=118 time=5.71 ms
64 bytes from 8.8.4.4: icmp_seq=4 ttl=118 time=5.36 ms
^C
--- 8.8.4.4 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3004ms
rtt min/avg/max/mdev = 5.302/5.507/5.715/0.175 ms
[tony@stapp01 ~]$
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