I don't understand why the plural version of дом is дома instead of домы. I had thought that the common rule was to add -и / -ы at the end of masculine words in the nominative form.
This masculine nouns plural ending -á, as opposed to the traditional -и/-ы, is a comparatively recent innovation. Even in the 19th century it was correct to say and write
учители (now it is "учителя"),
домы, etc. Look at the Ngram Viewer graph of the usage of
домы, it practically had stopped to be used by the 1920s, the same thing and the same years with
The plural ending -á first appeared in the low colloquial speech ("просторечие") and in the professional argots (шоферá 'drivers', слесаря́ 'turners' as opposed to the correct standard шофёры, слéсари) and later, as the graphs show, after the 1917 revolution, this ending started to infiltrate the written speech.
The masculine nouns with the plural ending -á are too many for all of them to be listed here, you just need to consult the dictionary, but I am sure, Russian textbooks will always point out the nouns that have the plural ending -á. Take such nouns as irregular, that's all I can recommend, there are no rule that can help you tell such nouns.
Also note, that some nouns can have both endings, with different meaning:
тонá (about color) and тóны (about sound)
хлебá (field(s) of wheat, rye) and хлéбы (loafs of bread)
And sometimes both endings are correct: штормá and штóрмы 'storms', годá and гóды 'years' (but only гóды in годы юности 'the years of youth', девяностые годы 'the nineties').
Again: dictionaries rule.
There is always a problem with "common rules" in Russian. As in Vysotsky's song:
Мы говорим не "штормы", а "шторма" -
Слова выходят коротки и смачны:
"Ветра" - не "ветры" - сводят нас с ума,
Из палуб выкорчевывая мачты.
Many nouns have plural ending in -ы/-и, yet some only -а (e.g. sleeves = рукава), some both (storms = штормы/шторма; winds = ветры/ветра), and some even have different meanings (хлебы = loafs of bread; хлеба = cereals).
Some examples are easily understandable, e.g "глаза" (eyes) ends in -а, because the old dual form won over plural. But why it is "мастера" (masters, craftsmen), and not "мастеры" - I can't say for sure. Just take it as is.
As Зализняк noted, Russian language currently has conflicting rules: old ones and new ones. They fight over words.
The new rule is that in plural form, the stress (ударение) should fall on a different syllable.
And indeed it does in the pair дом - дома.
It could not do that when plural was домы since the stress on ы is uncommon and very colloquial (кран - краны as some people say).
I'm not pretending this to be universal because it doesn't readily explain провод - провода. Where also exists an omonym проводы.