A system and method for dynamic selection of reliability by data publishing protocol while publishing data, comprising a constrained gateway device (102) being adapted to publish data by using a data publisher and adapted to send and receive acknowledgment messages, one or more subscriber devices (104) communicatively coupled with the constrained gateway device (102) and subscribed to the server (106) and adapted to send and receive acknowledgment messages, and a server (106) communicatively coupled with the constrained gateway device (102) and the one or more subscriber devices (104) and adapted to exchange the acknowledgement messages between the data publisher on the constrained gateway device (102) and the one or more subscriber devices (104) wherein the data publisher running on the constrained gateway device (102) has multiple reliability levels for publishing data and is adapted to dynamically select the reliability level based on available bandwidth and energy.