This file includes the following information on each decedent, if the data is available to the SSA:
Last name, First name, SS#, (State issued), Birth date,
Death date, Last residence/Lump sum payment.
The absence of a particular person in the SSDI is not proof this person is alive. Additionally, there is a possibility that incorrect records of death have been entered on the DMF. The Social Security Administration does not guarantee the accuracy of the file.
When you know the information, be as specific as possible to avoid a large of hits. (Large can be somewhere over a couple hundred or so.) If you are unable to find someone you are looking for, here are some things to try:
Change dates around (e.g. instead of searching for 5 Oct 1954 [10/5/54], search for 10 May 1954 [5/10/54]) Change years around (e.g. 1984 becomes 1948). Use all other possible spellings of the name (and perhaps some that aren't so likely). Switch last name and first name around. Try searching for a middle name as a first name. Even if you know a piece of information, try omitting it (e.g. if you know first and last name and death date, try leaving off the first name).