BNSHosting has recently coordinated with several larger ISPs and Telcos in the Philippines to correct some possible DNS spoofing issues. The symptoms are that the targetted website is not being resolved properly by other ISP’s DNS.
This article from US CERT on DNS vulnerability (http://www.kb.cert.org/vuls/id/800113) may shed some light. Some excerpts are reproduced below:
Caching DNS resolvers are primarily at risk–both those that are open (a DNS resolver is open if it provides recursive name resolution for clients outside of its administrative domain), and those that are not. These caching resolvers are the most common target for attackers; however, stub resolvers are also at risk.
An attacker with the ability to conduct a successful cache poisoning attack can cause a nameserver’s clients to contact the incorrect, and possibly malicious, hosts for particular services. Consequently, web traffic, email, and other important network data can be redirected to systems under the attacker’s control