Skip to content

Posts tagged ‘level3’


Updated: DNS resolution issues in DFW area

Beginning around 0700 CST, we detected DNS resolution issues in the DFW area (north Texas), particularly on AT&T’s network (i.e. iPhones using 3G), but also with corporate DNS servers going to the root hint servers. Time Warner Cable seems to be unaffected and neither does Airband (a local microwave-based ISP).

As a stop-gap, we implemented forwarders (, and regained a significant amount of resolution. At this point (0826 CST), we’re seeing resolution starting to come back, but certain sites like fail to load content.

Are you seeing anything in your part of the world?

Update from our ISP:

At approximately 3:30 a.m., <DFW provider> began experiencing intermittent internet connectivity.  While troubleshooting we realized we could get to some networks and could not reach other networks.  We narrowed the issue to Level3 who is having a problem with a BGP router located here in Dallas.  We have a ticket open with them and they will inform us once they have resolved their issue.  In the mean time, we have shutdown our Level3 connectivity until this issue is resolved.  We will advise you when we have restored the link after Level 3 has resolved the their issue…

Thus, it appears we have our root cause for north Texas issues: Level3. This also coincides with the partially successful use of Level3 forwarders (, .3) for DNS because it kept resolution on their network (connectivity to other backbones may have been an issue).