According to the accounts of Ibn Batutta, what was 'dawa'?

Foot-post Horse-post Secret messenger none of the above

Foot-post

Ibn Batutta described the Indian postal system as very efficient. There were two kinds of the postal system. The horse-post, called uluq, was run by royal horses stationed at a distance of every four miles. The foot-post had three stations per mile, it was called 'dawa', which is one-third of a mile.