This paper provides an overview of the distributed ledger technology (DLT) options available to central banks for issuing central bank digital currency (CBDC). We discuss the main requirements that a DLT solution must fulfill and analyze the various structures for implementation offered by DLT - public, permissioned and private - and the implications that each has for the central bank and the existing financial system. While a CBDC built on an open, permissionless system would provide the full functionality offered by DLT, it is also far more disruptive to the existing financial system and consequently requires more new infrastructure on the part of the central bank.