Is /etc/resolv.conf useless in Ubuntu 12.04 LTS ? I say so, because when I configured the /etc/resolv.conf file and rebooted the VM, all the settings were overwritten.
piyush@co109044:~$ cat /etc/resolvconf/resolv.conf.d/tail
search romelab.it.ibm.com ibm.com
nameserver 9.168.127.100
namserver 9.168.96.100
piyush@co109044:~$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
search romelab.it.ibm.com ibm.com
nameserver 9.168.127.100
namserver 9.168.96.100
piyush@co109044:~$ reboot
Last login: Mon Mar 31 08:48:50 2014 from 9.77.94.202
piyush@co109044:~$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
After rebooting the VM, all the settings of /etc/resolv.conf were overwritten.search romelab.it.ibm.com ibm.com
nameserver 9.168.127.100
namserver 9.168.96.100
piyush@co109044:~$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
search romelab.it.ibm.com ibm.com
nameserver 9.168.127.100
namserver 9.168.96.100
piyush@co109044:~$ reboot
Last login: Mon Mar 31 08:48:50 2014 from 9.77.94.202
piyush@co109044:~$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
After reading the release notes of Ubuntu, figured out that "resolvconf is now used to manage /etc/resolv.conf on all Ubuntu systems". What's that ??? I suggest reading the man page for resolvconf.
resolvconf is a set of script and hooks managing DNS resolution. The most notable difference for the user is that any change manually done to /etc/resolv.conf will be lost as it gets overwritten next time something triggers resolvconf or the system is rebooted. As a thumb rule, if you are using static IP configuration for your Ubuntu system, add all your network related entries to the file /etc/network/interfaces
piyush@co109044:~$ man resolvconf
piyush@co109044:~$ vi /etc/network/interfaces
piyush@co109044:~$ sudo vi /etc/network/interfaces
[sudo] password for piyush:
piyush@co109044:~$ cat /etc/network/interfaces
auto eth0
iface eth0 inet static
address 9.168.109.44
netmask 255.255.255.0
gateway 9.168.109.254
dns-nameservers 9.168.127.100 9.168.96.100
dns-search romelab.it.ibm.com ibm.com
auto lo
iface lo inet loopback
piyush@co109044:~$ ping google.com
ping: unknown host google.com
piyush@co109044:~$ sudo ifdown eth0;sudo ifup eth0
ssh stop/waiting
ssh start/running, process 1999
piyush@co109044:~$ ping google.com
PING google.com (173.194.41.167) 56(84) bytes of data
piyush@co109044:~$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 9.168.127.100
nameserver 9.168.96.100
search romelab.it.ibm.com ibm.com
As you can see the entries from the /etc/network/interfaces were automatically added to the /etc/resov.conf file. Notice that the /etc/resolv.conf is a softlink to /run/resolvconf/resolv.confpiyush@co109044:~$ vi /etc/network/interfaces
piyush@co109044:~$ sudo vi /etc/network/interfaces
[sudo] password for piyush:
piyush@co109044:~$ cat /etc/network/interfaces
auto eth0
iface eth0 inet static
address 9.168.109.44
netmask 255.255.255.0
gateway 9.168.109.254
dns-nameservers 9.168.127.100 9.168.96.100
dns-search romelab.it.ibm.com ibm.com
auto lo
iface lo inet loopback
piyush@co109044:~$ ping google.com
ping: unknown host google.com
piyush@co109044:~$ sudo ifdown eth0;sudo ifup eth0
ssh stop/waiting
ssh start/running, process 1999
piyush@co109044:~$ ping google.com
PING google.com (173.194.41.167) 56(84) bytes of data
piyush@co109044:~$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 9.168.127.100
nameserver 9.168.96.100
search romelab.it.ibm.com ibm.com
So if you make, /etc/resolv.conf as a regular file then resolvconf will be disabled (not recommended).
Resolvconf has a /etc/resolvconf/resolv.conf.d/ directory that can contain "base", "head", "original" and "tail" files. All in resolv.conf format.
- tail: Any entry in /etc/resolvconf/resolv.conf.d/tail is appended at the end of the resulting resolv.conf. If the tail file is missing then create it.
- base: Used when no other data can be found.
- original: Just a backup of your resolv.conf at the time of resolvconf installation
ReplyDeleteHmm, it seems like your site ate my first comment (it was extremely long) so I guess I’ll just sum it up what I had written and say, I’m thoroughly enjoying your blog. I as well as an aspiring blog writer, but I’m still new to the whole thing. Do you have any recommendations for newbie blog writers? I’d appreciate it.
Advanced AWS Interview Questions And Answers, Top 250+AWS Interviews Questions and Answers 2018
Advanced AWS Interview questions and answers | Top 110 AWS Interview Question and Answers
Advanced AWS Training in Bangalore | Best Amazon Web Services Training in Bangalore
Advanced AWS Training in Pune | Best Amazon Web Services Training in Pune
Advanced AWS Online Training | Best Online AWS Certification Course in india
This is such a great post, and was thinking much the same myself. Another great update.
ReplyDeletepython Online training in chennai
python Online training in bangalore
python interview question and answers
I would really like to read some personal experiences like the way, you've explained through the above article. I'm glad for your achievements and would probably like to see much more in the near future. Thanks for share.
ReplyDeleteSelenium Online training | Selenium Certification Online course-Gangboard
Selenium interview questions and answers
Selenium interview questions and answers
Selenium Online training | Selenium Certification Online course
Great Article… I love to read your articles because your writing style is too good, its is very very helpful for all of us and I never get bored while reading your article because, they are becomes a more and more interesting from the starting lines until the end.
ReplyDeleterpa training in chennai
Best rpa training in bangalore
rpa course in bangalore
rpa training in marathahalli
rpa training in btm
best rpa training in chennai
Its really an Excellent post. I just stumbled upon your blog and wanted to say that I have really enjoyed reading your blog. Thanks for sharing....
ReplyDeleteBest Devops training in sholinganallur
Devops training in velachery
Devops training in annanagar
Devops training in tambaram
Really very nice blog information for this one and more technical skills are improve,i like that kind of post.
ReplyDeleteData Science training in Chennai | Data Science Training Institute in Chennai
Data science training in Bangalore | Data Science Training institute in Bangalore
Data science training in pune | Data Science training institute in Pune
Data science online training | online Data Science certification Training-Gangboard
Data Science Interview questions and answers
Data Science Tutorial
ReplyDeleteWhoa! I’m enjoying the template/theme of this website. It’s simple, yet effective. A lot of times it’s very hard to get that “perfect balance” between superb usability and visual appeal. I must say you’ve done a very good job with this.
AWS TRAINING IN BANGALORE|NO.1AWS TRAINING INSTITUTES IN BANGALORE