Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

My Comcast internet connection has been giving problems in DNS resolution, and I am guessing the reason is a probably broken or limited UDP. I am currently working around it by tunneling over TCP through a VPN, but to get the IP address of the server hosting the VPN I had to do a dig @ +tcp <hostname>.

I am wondering if there is a configuration to enforce DNS resolutions over TCP instead of UDP?

share|improve this question (not tested)

Something like that should work?

share|improve this answer

The glibc has a use-vc option to force TCP. The OpenBSD libc has a tcp option. However the FreeBDS, DragonFlyBSD and NetBSD do not have this option AFAIK. Mas OS/X / Darwin libresolv does not seem to have a corresponding option (same as FreeBSD, NetBSD, DragonFlyBSD).

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.