mount: unknown filesystem type 'cifs'

For some reason, I can mount my NAS using cifs as follows:

sudo mount -t cifs //10.0.0.210/data -o username=xxxxxxxxxxxxx,password=xxxxxxxxxxx,rw,nounix,iocharset=utf8,file_mode=0644,dir_mode=0755 /mnt/nas

But when I enter this into my fstab:

//10.0.0.210    /mnt/nas   cifs  username=xxxxxxxxxxxxx,password=xxxxxxxxxxxxx,rw,nounix,iocharset=utf8,file_mode=0644,dir_mode=0755

And I run this:

sudo mount -a

I get this:

mount: unknown filesystem type 'cifs'

Any help here would be awesome. Thanks