While not immediately obvious you can manage external domains with TierraNet. Set up a free account with them and then go to the Manage DNS section of the website. The page says you have to pay $7.95 for the DNS zones if you don't use their paid services elsewhere, but the system will let you add the zones without paying, thus performing the takeovers. After performing the takeover you will be sent a bill via email. If you then remove the zone they will wave the fee.
Yes, you can perform DNS takeovers of domains pointing to TierraNet's DNS service.
ServiceTierraNetStatusVulnerableNameserverExplanationWhile not immediately obvious you can manage external domains with TierraNet. Set up a free account with them and then go to the Manage DNS section of the website. The page says you have to pay $7.95 for the DNS zones if you don't use their paid services elsewhere, but the system will let you add the zones without paying, thus performing the takeovers. After performing the takeover you will be sent a bill via email. If you then remove the zone they will wave the fee.