Now playing: Watch this: DNSChanger dead, now what?

The FBI today made good on its promise to take down its DNSChanger network. But people who ignored warnings may find themselves unable to get online.

At 12:01 a.m. EDT today, the FBI shut down the DNS servers that had kept computers infected by the DNSChanger malware still able to connect to the Internet, according to the Washington Post.

About five years, a group of hackers who deployed the DNSChanger malware, which modified the DNS settings of infected computers to point to rogue servers. After catching the criminal gang and taking controls of the servers, the FBI converted those machines into legitimate DNS computers last year to ensure that infected computers would still have online access.

But today was the deadline to shut down that temporary network, kicking affected users offline unless they followed previous alerts to modify their DNS settings.

How many people could be taken offline by the shutdown?

Opinions seem to vary, pointing to as few as several thousand or as many as 300,000. Of the more than 570,000 computers originally infected, around 250,000 are still bit by the virus, according to the Post.

However, Internet service providers have been trying to work with their customers to help restore their correct DNS settings. Comcast has already contacted users with infected computers, says the Wall Street Journal. Verizon has lined up technicians who can help customers remove the virus. And AT&T plans to redirect infected PCs to the correct Web sites.

So the effect of the shutdown should be minimal, at least according to the ISPs.

People who are unable to get online should call their ISP to see if their computers are infected. CNET has also posted a how-to guide to help people detect whether their PCs are pointing to the DNSChanger network.