Lost DNS lookup (SOLVED)

McGuffey, David C. DAVID.C.MCGUFFEY at saic.com
Wed Jul 2 15:27:12 UTC 2008

In a previous message I wrote:
> A few days ago, a workstation in a lab stopped doing DNS lookups to
> support connectivity to SMTP, POP, and web services.  As I think back,
> behavior started in close proximity in time to a stunnel update.
> Checked the usual locations and all seems to be ok.  /etc/resolv.conf,
> /etc/nsswitch.conf, /etc/host and /etc/networks files look ok.
> ifconfig in a terminal shows that DHCP on the boundary firewall gave
it a
> good address, netmask, and gateway. The machine still serves up an
> partition via samba to some windowze machines on the
> and still prints to two network printers via cups (same
> network), so it is not a hardware problem. The two other windowze
> on the network can reach the web via Firefox, but the fedora 7 box
> so I don't believe it is a firewall problem (nothing has changed
> As a last resort, I executed the normal windowze solution...a reboot.
> That did not solve the problem.
> Lights on the local 8-port switch don't seem to indicate any network
> traffic when an nslookup command is issued.  I don't believe it is
> DNS requests through the gateway to the dns server...but will confirm
> tshark later today/this evening.
> Any ideas?

Problem was a DHCP lease in an ISP provided router/firewall on our
boundary that we set to 6 minutes.

Per RFC, what normally happens when a lease expires?  I would think that
the host would ask for another IP and be back up on the net.

Dave McGuffey
Principal Information System Security Engineer // NSA-IEM, NSA-IAM
SAIC, IISBU, Columbia, MD

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