Reports are coming in that Yahoo was not accessible to a certain subset of users for well over an hour. It’s not exactly clear what happened, but the problem appears to have impacted a significant number of users. DBKP notes that complaints have been received from users in diverse locations like Virginia, USA and Mumbai, India.
A discussion on Neowin suggests that at least a portion of the affected users were having trouble due to issues with Comcast and AT&T’s DNS service. The problems seem to have been resolved for most users. However, in case you are still having trouble accessing Yahoo Search or Yahoo Mail, try your luck with alternate DNS services like OpenDNS and Google Public DNS. If you are not comfortable with manually changing your DNS settings, DNS Jumper can do it automatically for you.
Yahoo has been accessible on my end throughout the day. However, I use OpenDNS, which apparently is not affected by this outage. Don’t forget to let us know if Yahoo is/was down for you.