I have read the criteria for the "Announcer" badge, and I am not sure if I understand this correctly.
Share a link to a question later visited by 25 unique IP addresses
The intention of the word unique in this criteria is to ensure that the question is visited by 25 people. However, if 25 students in the same school/company visit that shared link, no "Announcer" badge will be awarded if they share the same IP.
Moreover, the same user may visit the shared link in different places in order to gain this badge.