Track

Often when a PC uses Survival to Track, you can pick a simple DC and adjust it based on the circumstances. For example, an army is usually easy to track, so you could use the untrained DC of 10. If the army drove tanks through mud, you could even adjust this down to DC 5. On the other hand, if the party pursues a cunning spy using Cover Tracks, you might use their Survival DC as the DC to Track. If the character is familiar with the terrain, you might want to apply an easy adjustment.