I reported earlier today that there had been some major issues affecting the DNS system on the Internet.
To recap, the DNS infrastructure is used to map domain names (like dailykos.com) to IP addresses, (like 208.122.51.48). If the DNS system was not functioning properly, then you wouldn't be able to access websites by using the domain name, sending email to certain domains wouldn't work, and there'd just be a lot of Internet brokenness.
There was a problem that affected one of the largest players in the DNS infrastructure, and it now appears that was caused by an intentional attack.
That provider is Network Solutions, which hosts the DNS record information for a huge number of domains. Network Solution is one of the oldest and most established DNS registrars, and over the past two days, there have been numerous reports of people having trouble accessing domains that are maintained by Network Solutions.
While it is fixed now, Network Solutions now does in fact confirm that these problems were the result of a Distributed Denial-of-Service (DDoS) attack. This means that there was an organized, coordinated attack by some malicious third party.
There are no details yet as to who coordinated the attack or where they came from. But they do reveal that though the Internet is a wide, distributed network, there are still some very vulnerable choke-points, especially the DNS system, that leaves the entire network vulnerable to an attack.
Things are fixed now, but we've seen this type of attack in the past and we'll probably see more in the future.