Shayan Shah: Its not easy to find good expired domain, if you`re expired domain have bad backlinks it effect your whole ranking, but if youre expired domain has good high authority backlinks then its like a dimaond.
Ammon Johns: It has been literally decades since Google became a domain registrar, giving them inside access to the source data on when domains expire, when they are purchased, and where they are both registered to, and pointed at.
Not only that, Google also operate a DNS server that anyone can use.
The above make it absolutely a cast-iron fact that they know about domains expiring long, long before you do.
Furthermore, Google keep data on when they last crawled, and they have a full cache of the page as crawled.
So they know when a site has a dramatic change too.
Given those absolute and undisputed facts, you can decide for yourself whether you think just buying expired domains, a trick widely and openly talked about literally 20 years ago, is any kind of secret trick that outsmarts Google.