National Public Data, one of the country’s biggest companies for background checks, has confirmed it suffered a data breach including full names, addresses, and social security numbers. Hackers claim to have stolen 2.9 billion records.After a data breach, one of the best things you can do to prevent fraud is to freeze your credit at the three credit agencies: Equifax, TransUnion, and Experian. Here are the three ways you can request to freeze your credit.OnlineThis is the fastest and easiest way to freeze your credit. You’ll need to create an account with each of the three credit bureaus to manage your credit freeze. The links to do so are below:EquifaxExperianTransUnionAgencies must freeze your credit within one business day of your online request.By phoneYou can call each of the three credit bureaus at the following numbers to request a credit freeze:Equifax: (888) 298-0045Experian: 888-397-3742TransUnion: 800-916-8800Agencies must freeze your credit within one business day of your request by phone.By mailYou can send letters to each of the credit bureaus requesting a credit freeze. You can find the necessary addresses and additional information at the following links: EquifaxExperianTransUnionAgencies must freeze your credit report within three business days of your request by mail.Have a question for Jeff Rossen? He’s answering your consumer questions every Friday in the new segment "Rossen Responds." Email your questions to him at RossenResponds@hearst.com. Want bonus content and exclusive deals? Make sure to sign up for our free newsletter at RossenReports.com.