An RPM spec file, among other things, enumerates a list of required packages under the BuildRequires tag. Every package listed must be installed on the build platform otherwise the build will fail.
You can install the necessary BuildRequires packages either manually using yum or even rpm, but a easier way to do so is to use a utility called yum-builddep which is part of the familiar yum-utils package.
$ sudo yum-builddep 389-ds-base-1.2.9.9-1.fc14.src.rpm
If all goes well, all the dependency packages are automatically installed for you.
Unfortunately yum-builddep does not know how to handle conditional BuildRequires and will sometimes incorrectly include or exclude a BuildRequires. In this case you have to manually install the build dependencies.
