Delay Tolerant Networks (DTNs) is a network, where synchronous connectivity among all nodes doesn't exist i.e. end to end connectivity not mandatory to be present. The major problem of DTN is how to route a packet from one terminal to another. Due mobility of nodes, unreliable and temporary connectivity the routing problem becomes more complex. It is very tedious to design the routing protocol for such kind networks. This work surveys the various routing techniques.

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