One baraita that is quoted by the Gemara rules that a Beit haKnesset as well as a house belonging to a woman or a house that is owned by two or more partners is obligated in mezuza. In response to the question Peshita!? – isn’t this obvious!? – the Gemara argues that we may have thought that the passage obligating beitekhah (“your house” in the singular, masculine – see 11:20) limits the mitzva to a single, male owner. Since, however, the mitzva of mezuza offers the promise of a long life ( 11:21), it is applied to everyone who deserves and desires such – including women.
Many commentaries ask why this particular passage is chosen for distinction. Given that most of the Torah is written in the masculine, yet is applied to all Jews, why should we make a particular point of emphasizing that this mitzva may only have been applied to men? The Gevurot Ari points out that we are dealing with a unique case. The entire parasha was written in the plural, with the single exception of the passage about mezuza, which is written in the masculine. Thus it is reasonable to consider the possibility that it refers specifically to men.
Another rule taught on this daf is the obligation to have mezuzot checked twice every seven years in a private home, and twice every 50 years in public places. Rashi explains the difference based on the principle that we try to keep from disturbing the public. The Sefer HaEshkol says that it is a practical issue. A mezuza in a public place is seen by all, and if there was a problem with it, it would be noticed by someone who would bring it to the attention of the authorities. The Rosh argues that checking a public mezuza carries with it an element of danger, an explanation that fits in with a story brought in the Gemara.
There was an incident involving an examiner [artavin], who was examining mezuzot in the upper marketplace of Tzippori during a period when decrees were issued against the Jewish people, and a Roman official [kasdor] found him and collected a fine of one thousand zuz from him.