The DNN (Data Network Name) is the 5G equivalent of the LTE APN — it identifies the target data network (e.g., "internet", "ims", "enterprise-vpn"). S-NSSAI (Single Network Slice Selection Assistance Information) identifies a specific network slice and consists of SST (Slice/Service Type, 8 bits) + optional SD (Slice Differentiator, 24 bits). Standard SST values: 1 = eMBB, 2 = URLLC, 3 = mMTC, 4 = V2X.