Although flights do not connect Hargeisa to other towns in Somaliland, the more normal mode of transport is by road. Conditions are variable.
The main road from Borama via Hargeisa, Berbera, Sheikh, Burao and Oog (the Garoowe border post with Somalia) is surfaced and can easily be covered in any sedan car.
All other roads, including the ones from Borama to Zeila, and Oog to Maydh via Erigavo, are unsurfaced and too rough to risk without a 4×4.
There are buses in Somaliland, but foreigners are usually permitted to use the inexpensive but jam-packed shared taxis that run along the stretch of road from Borama to Burao, via Hargeisa and Berbera, and also to travel in the 4x4s that connect Hargeisa and Burao to Zeila and the Djibouti border.
Other parts of the country may only be visited in a 4×4 with a local driver, which can be rented through one of the agencies in Hargeisa. From what we know, self-drive car rental is not an option in Somaliland. It could be that overlanders with their own vehicle are permitted to drive themselves with SPU protection.