As in indicated earlier, qaafiyaa can be exact, nearby or open. This is clearly mentioned in the search results.
The selection of a set of qaafiyaas for a ghazal is closely linked to the matla (first sher of the ghazal).The same type of qaafiyaa (exact or close or open) that is used in the matla should follow in the rest of the misras.

1) Example of Exact Qaafiyaa:

If matla is...

ab kyaa soche.n kyaa haalat the kis kaaran ye zahr piyaa hai
hum ne us ke shahr ko chhoDaa aur aankho.n ko mund liyaa hai

As we can see above sher that both misras has used qaafiyaas which has rhyming pattern of --yaa thus all other qaafiyaas in the ghazal will follow this patter such as:

piyaa, liyaa, kiyaa, liyaa ,jiyaa, diyaa

2) Example of close Qaafiyaa:

If matla is...

aa.ina samne rakhoge to yaad aa.u.ngaa
apni zulfon ko sanwaroge to yaad aaunga

As we can see above sher that both misras has used qaafiyaas which has rhyming pattern of --oge, thus all other qaafiyaas in the ghazal will follow this patter such as:

KHaridoge, chaahoge, baiThoge, bhigoge, nikaloge, guzroge

3) Example of open Qaafiyaa:

If matla is...

aadmii aadmii se miltaa hai
dil magar kam kisii se miltaa hai

As we can see above sher that both misras has used qaafiyaas which has rhyming pattern of --ii, thus all other qaafiyaas in the ghazal will follow this patter such as:

Saadgii, hansii, KHush-qaamatii, be-KHuudii, ham-saaegii

If the matla is not written first then, the poet should take care that the above rules are followed for the matla based on the qaafiyaas used in other shers.