Link: how to recognise expired domains

Domain purchasing albeit an old method, it is still a valid technique to obtain value in the links. The utility is essentially found in link building, but it is always appropriate to behave correctly. When a domain already has an owner but it is not used frequently, Google receives a signal that detects abnormal behaviour and acts accordingly.

The reasons why this happens is that while launching the same identical signal to Montain View, it can be from multiple sources: 

• Expired domains: are no longer of any use to the old owner and, therefore, are cheap. This is the simplest signal to decipher for Google.
• Domains up for sale and parked domains: they are both classes of opportunities that send signals to Google. As a rule, a domain that is already on sale is a sign for Google, but when the acquisition, hosting and change of contents are combined, the signal becomes clearer. To this end, it is advisable to refrain from performing these actions at the same time and try to re-propose the original content. 
• Bankruptcy (due to insolvency or bankruptcy): in these cases the domain becomes available again. These domains can be rich in connectivity value. The deal becomes particularly lucrative especially in cases where the company is not kept alive by anyone and, therefore, is not aware of the real value of the links. If implemented cleverly, the purchase will not reveal the obfuscated SEO intent to Google.
• Conferences and obsolete events: When you have to organise events or conferences, you buy one-year domains. After a couple of years, obviously, they will not receive any more visits. This is just the right time to make the offer.
• Absence of activity: requires an accurate search to verify that the site on the domain has not been updated for some time. This feature is a clear indicator of the owner's lack of interest in the site and, therefore, the domain could be sold at an affordable price.