The addresses for those rarely change, some are unlikely to change in a lifetime. They have the same addresses year after year. You are free to keep looking them up every day, but, with very few exceptions, they will still be the same. Don't take my word for it, try storing these addresses for the major TLDs. With very few exceptions, they will work for decades. I know the addresses for a root and a .com server from memory. They do not change.
In practice everyone finds the designated authoritative servers through the root servers and TLD servers. They're trusted already.