DL meaning in Military and Defence ?

Distance education, also called distance learning, is the education of students who may not always be physically present at a school. Traditionally, this usually involved correspondence courses wherein the student corresponded with the school via mail. Today, it usually involves online education. A distance learning program can be completely distance learning, or a combination of distance learning and traditional classroom instruction (called hybrid or blended). Massive open online courses (MOOCs), offering large-scale interactive participation and open access through the World Wide Web or other network technologies, are recent educational modes in distance education. A number of other terms (distributed learning, e-learning, m-learning, online learning, virtual classroom etc.) are used roughly synonymously with distance education.