Thursday, 28 August 2014

How Update DNS Records in Local Linux Machine - [ Ubuntu ]

Created Thursday 28 August 2014

By TDL Matias




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This tutorial is to use as my own keep track record of things I do everyday with Linux.. I had to install a new linux distro into a user computers, the distro in question was Ubuntu 12.04 - 64bit.

I have gave the machine a name = DevOps14 with IP 172.xx.xx.184 - The problem is that that same machine, had being installed on the intranet before with same hostname (DevOps14) and had assigned previously the IP address 172.xx.xx.185 ..

after installed, I tried to access it using the hostname, I was getting network names conflit errors ..

When I tried to ping it .. I was getting the following error ...


user@host1:~$ traceroute -n devops14.uk.domain
traceroute to devops14.uk.domain (172.xx.xx.185), 30 hops max, 60 byte packets
1 172.16.14.70 2996.257 ms !H 2996.201 ms !H 2996.180 ms !H

user@host1:~$ ping -c 3 devops14.uk.domain
PING devops14.uk.domain(172.xx.xx.185) 56(84) bytes of data.
From host1.uk.domain (172.xx.xx.xx) icmp_seq=1 Destination Host Unreachable
From host1.uk.domain (172.xx.xx.xx) icmp_seq=2 Destination Host Unreachable
From host1.uk.domain(172.xx.xx.xx) icmp_seq=3 Destination Host Unreachable


--- devops14.uk.domain ping statistics ---
3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2014ms


Then, I went and updated our DNS server records usind rndc tool ... Tried do ping the devops14 again .. but not avail ..


user@host1:~$ ping -c 3 devops14.uk.domain
PING devops14.uk.domain (172.xx.xx.185) 56(84) bytes of data.
From host1.uk.domain (172.xx.xx.xx) icmp_seq=1 Destination Host Unreachable
From host1.uk.domain (172.xx.xx.xx) icmp_seq=2 Destination Host Unreachable
From host1.uk.domain (172.xx.xx.xx) icmp_seq=3 Destination Host Unreachable


---devops14.uk.domain ping statistics ---
3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2000ms
pipe 3



Ok then ..IF I have updated the DNS - Records, theres no reason that I could not ping that machine right into the IP - 172.xx.xx.184 instead of 172.xx.xx.185 ... Something was no really adding up ...


So I went into https://www.google.com/ to investigate and se if someone had come accross the same issue it was then when I found in a Ubuntu forum [http://askubuntu.com/questions/414826/how-to-flush-dns-in-ubuntu-12-04 ]


That I had only to refresh the network DNS record on my local machine with this command.


user@host1:~$ sudo /etc/init.d/nscd restart
* Restarting Name Service Cache Daemon nscd                                                                      [ OK ]



And then PING it again ....


user@host1:~$ ping -c 3 devops14.uk.domain
PING devops14.uk.domain (172.xx.xx.184) 56(84) bytes of data.
64 bytes from devops14.local (172.xx.xx.184): icmp_seq=1 ttl=64 time=0.582 ms
64 bytes from devops14.local (172.xx.xx.184): icmp_seq=2 ttl=64 time=0.139 ms
64 bytes from devops14.local (172.xx.xx.184): icmp_seq=3 ttl=64 time=0.103 ms


---devops14.uk.domain ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2000ms rtt min/avg/max/mdev = 0.103/0.274/0.582/0.218 ms




 All working fine now ...