DNS not being populated in resolv.conf

[Tom H]

On Sun, Nov 28, 2010 at 7:15 AM, Kaushal Shriyan
<kaushalshriyan at gmail.com> wrote:
> On Sun, Nov 28, 2010 at 4:55 PM, Tom H <tomh0665 at gmail.com> wrote:
>> On Sun, Nov 28, 2010 at 1:34 AM, Kaushal Shriyan
>> <kaushalshriyan at gmail.com> wrote:
>> > On Sat, Nov 27, 2010 at 1:21 PM, Tom H <tomh0665 at gmail.com> wrote:
>> >> On Fri, Nov 26, 2010 at 9:08 PM, Kaushal Shriyan
>> >> <kaushalshriyan at gmail.com> wrote:
>> >> >
>> >> > I have three Internet Service Provider to connect to internet from my
>> >> > laptop
>> >> > running Ubuntu Desktop Linux OS 10.04
>> >> > For example ISP A, ISP B ISP C
>> >> > ISP A  --> is the Office Network (when i am in office )
>> >> > ISP B -->  is the Mobile Broadband Network (when i am moving )
>> >> > ISP C --> is the Home Network (when i am at home)
>> >> > Also in addition to the above details :-
>> >> > I have local DNS Server at office, DNS server of Data Center 1 and
>> >> > DNS
>> >> > Server of Data Center 2. so whenever i am in office, by default i
>> >> > need
>> >> > to
>> >> > connect to these
>> >> > three DNS Servers in order to access the servers.
>> >> > The steps i have followed after using resolvconf
>> >> > sudo apt-get install resolvconf
>> >> > sudo rm /etc/resolv.conf
>> >> > sudo ln -s /etc/resolvconf/run/resolv.conf /etc/resolv.conf
>> >> > sudo vim /etc/openvpn/update-resolv-conf
>> >> >
>> >> > Add the following lines in the beginning.
>> >> >
>> >> > foreign_option_1='dhcp-option DOMAIN off.example.com dc1.example.com
>> >> > dc2.example.com'
>> >> > foreign_option_2='dhcp-option DNS 172.26.0.1'
>> >> > foreign_option_3='dhcp-option DNS 10.20.0.1'
>> >> > foreign_option_4='dhcp-option DNS 10.20.0.2'
>> >> > foreign_option_5='dhcp-option DNS 10.30.0.1'
>> >> > save and exit
>> >> > Add the below two lines at the bottom of the file openvpn client
>> >> > DC1.conf
>> >> >
>> >> > up /etc/openvpn/update-resolv-conf
>> >> > down /etc/openvpn/update-resolv-conf
>> >> > The issue which i am facing is that I am unable to resolve the local
>> >> > DNS
>> >> > Servers at office. I need the local DNS Server in order to access
>> >> > Network
>> >> > printers
>> >> > and other devices.
>> >> > Office DNS Server is off.example.com and DNS Server IP is 172.26.0.1
>> >>
>> >> Are all five options above for your office network?
>> >
>> > Not sure i understand that ?
>> >>
>> >> Please post "cat /etc/resolv.conf" after you connect to your office
>> >> network.
>> >
>> > cat /etc/resolv.conf in my Ubuntu Laptop Desktop PC running 10.04
>> > search off.example.com  ### office
>> > search dc1.example.com ### DataCenter No.1
>> > search dc2.example.com' ### DataCenter No. 2
>> > DNS 172.26.0.1
>> > DNS 10.20.0.1
>> > DNS 10.20.0.2
>> > DNS 10.30.0.1
>>
>> This "resolv.conf" is incorrect.
>>
>> The "DNS" lines don't mean anything. It shouldn't be "DNS" but
>> "nameserver".
>
> sorry there was a typo, it is actually nameserver
>
>> The "search" lines don't make sense (although I could be wrong). I
>> don't use "search" but I'd expect your "resolv.conf" to have one
>> search line "search example.com" with your domain and not three with
>> boxes.
>
> search off.example.com  ### office
> search dc1.example.com ### DataCenter No.1
> search dc2.example.com' ### DataCenter No. 2
> nameserver 172.26.0.1
> nameserver 10.20.0.1
> nameserver 10.20.0.2
> nameserver 10.30.0.1
> Are you saying it should be as below  :-
> foreign_option_1='dhcp-option DOMAIN off.example.com' ### office
> foreign_option_2='dhcp-option DOMAIN dc1.example.com' ### DataCenter No.1
> foreign_option_3='dhcp-option DOMAIN dc2.example.com' ### DataCenter No.2
> foreign_option_4='dhcp-option DNS 172.26.0.1' ### office
> foreign_option_5='dhcp-option DNS 10.20.0.1'  ### DataCenter No.1
> foreign_option_6='dhcp-option DNS 10.20.0.2'  ### DataCenter No.1
> foreign_option_7='dhcp-option DNS 10.30.0.1'  ### DataCenter No.2
>>
>> (I'd asked whether the five "foreign_option_X" were for your three
>> locations or just for your office.)
>
> foreign_option_X was for the three locations viz office,data center 1 and
> data center 2

OK for "nameserver".

No, I wasn't suggesting the you spread the "search" values over three
lines. I was curious as to how the script that's putting your
"resolv.conf" together could distinguish between your locations. Since
you only have your office DNS settings, it's not relevant.

I'm still not clear on "search off.example.com dc1.example.com
dc2.example.com". Are off.example.com, dc1.example.com,
dc2.example.com subdomains of example.com or servers? For example, I'd
assumed that "dcX..." referred to AD DCs.

Is a host, whose short name is "box", in your office called
"box.off.example.com" or "box.example.com"?

Since your "resolv.conf" is correct, assuming that you've used the
correct DNS server ip addresses, what happens when you run a DNS
query?

What's the output of
grep hosts /etc/nsswitch.conf
dig +trace office_server
dig +trace +nosearch office_server