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Due to changes in the LAN router, I had to modify the static IP of one of our servers. It still succeeds in finding the external world (ping google.com), but only temporarily - when I access one of the websites hosted in that server through a browser, if that website tries to access google.com, for example, ping stops returning successful requests.

All computers can still ssh into the server, the problem seems to be DNS-related only: the server itself can't connect to the outside through domain names reliably.

/etc/network/interfaces

[...]
# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth1
iface eth1 inet static
        address 192.168.0.53
        netmask 255.255.255.0
        network 192.168.0.1
        broadcast 192.168.0.255
        gateway 192.168.0.1
        dns-nameservers 8.8.8.8 8.8.4.4

/etc/resolv.conf

nameserver 8.8.8.8
nameserver 8.8.4.4
search phub.net.cable.rogers.com

Restarting the networking daemon or even rebooting the computer didn't solve the problem. Also, I don't think that the dhcp daemon is overriding any of those configs, because the problem remains even when I explicitly stop the client.

noobeana
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    I am not at all convinced that the issue you are describing is related to DNS. I suggest you fire up tcpdump to check though.. `tcpdump -ni any port 53` – Zoredache May 01 '14 at 17:27
  • Hi Zoredache. I got a huge output from `tcpdump`, ending with the following: 10 packets captured 10 packets received by filter 0 packets dropped by kernel – noobeana May 01 '14 at 17:35
  • I'm with Zoredache, this is almost certainly not a DNS issue. – Jed Daniels May 01 '14 at 18:59
  • This statement is confusing: "when I access one of the websites hosted in that server through a browser, if that website tries to access google.com, for example, ping stops returning successful requests." Can you please elaborate/explain it differently? – Jed Daniels May 01 '14 at 19:00
  • Hi @JedDaniels, what I meant is that there's a webserver (Apache2) installed on that machine. One of the sites hosted on Apache2 uses an external service (Mailchimp's API) to fetch data. Let's say that dev website is accessible through mysite.lanserver. Whenever I access that URL, mysite.lanserver tries to connect to the external service and everything breaks (the domain lookup times out both on Apache2 and `ping`). – noobeana May 01 '14 at 19:27
  • IP address conflict with the static IP you've assigned? –  May 01 '14 at 22:00
  • @yoonix, do you mean that another machine in the LAN might be using the IP reserved for that server? If that's what you mean, do you know an easy way of checking that? – noobeana May 02 '14 at 00:41
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    Yes. The easiest way would be to shut down the interface on the server with the problem and try to ping that address. If you get a reply then its confirmed. If you don't, look in your ARP table to see if it shows up there. –  May 02 '14 at 01:38
  • In addition, you may want to remove the "network 192.168.0.1". Almost noone uses alternate network/broadcast addresses anymore, and the correct one would be .0, not .1 – b0fh Sep 05 '14 at 14:28

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