Hi Ulf, Our issue was that 75.75.75.75 was not responding to queries at all and for some reason clients weren't getting redirected to 75.75.76.76. For us all is well now, my email was stuck in Nanog Approval land for a couple of days so I couldn't give an update to the list until today. Have a good day, Aaron [Description: Description: Description: logo-email] Aaron Childs, CCNA Associate Director, Networking Information Technology www.westfield.ma.edu/it<http://www.westfield.ma.edu/it> Please Note: new e-mail address - aaron@westfield.ma.edu<mailto:aaron@westfield.ma.edu> From: Ulf Zimmermann [mailto:ulf@alameda.net] Sent: Thursday, December 05, 2013 7:28 AM To: Childs, Aaron Cc: nanog@nanog.org Subject: Re: Comcast DNS Issue? Is your issue that it gives out old DNS records? Because I am trying to track something down for an user on Comcast who is still getting the old IP of a VPN concentrator. The DNS records has a TTL of 30 minutes, yet a week later the end user is still getting the old IP. Haven't been able to get him to query 75.75.75.75 and 75.75.75.76 directly to see if he gets the IP from there. On Tue, Dec 3, 2013 at 11:46 AM, Childs, Aaron <aaron@westfield.ma.edu<mailto:aaron@westfield.ma.edu>> wrote: Good Afternoon, If there is a Comcast DNS Engineer on the list could you contact me off-list? We are experiencing an odd issue with 75.75.75.75. Thanks, Aaron [Description: Description: Description: logo-email] Aaron Childs, CCNA Associate Director, Networking Information Technology www.westfield.ma.edu/it<http://www.westfield.ma.edu/it><http://www.westfield.ma.edu/it> Please Note: new e-mail address - aaron@westfield.ma.edu<mailto:aaron@westfield.ma.edu><mailto:aaron@westfield.ma.edu<mailto:aaron@westfield.ma.edu>> -- Ulf Zimmermann, 1525 Pacific Ave., Alameda, CA-94501, #: 510-396-1764 You can find my resume at: http://www.Alameda.net/~ulf/resume.html

Yes clients had both IPs in their relative DNS configuration settings. Aaron Childs, CCNA Associate Director, Networking Information Technology www.westfield.ma.edu/it Please Note: new e-mail address - aaron@westfield.ma.edu -----Original Message----- From: christopher.morrow@gmail.com [mailto:christopher.morrow@gmail.com] On Behalf Of Christopher Morrow Sent: Thursday, December 05, 2013 11:09 AM To: Childs, Aaron Cc: Ulf Zimmermann; nanog@nanog.org Subject: Re: Comcast DNS Issue? On Thu, Dec 5, 2013 at 11:02 AM, Childs, Aaron <aaron@westfield.ma.edu> wrote:

Our issue was that 75.75.75.75 was not responding to queries at all and for some reason clients weren't getting redirected to 75.75.76.76.

did the clients not have 75.75.76.76 in their resolv.conf (or equivalent) as the second nameserver entry? that 'redirect' is the host-os knowing it has more than one 'nameserver' to ask questions of, right? so without the config... you are SOL.