It is always recommended to implement RDC for Marketing Cloud ID Service and thus use ***.sc.omtrdc.net domain for tracking server to reduce latency and data loss related issues.
Basically ,Regional data collection is a network of regional data collection centers (DCC) that aim to reduce latency and data loss associated with Adobe image requests. Data is collected at DCC sites throughout the world, then immediately forwarded to the Data Processing Center for processing. Please see the following link for more info : https://marketing.adobe.com/resources/help/en_US/whitepapers/rdc/
Thanks & Regards
Thanks for the explanations. So does it mean, if I still use 2o7.net I can get the visitor ID but my data collected for the visitor will be obviously erroneous. Does my understanding is correct ?
That is correct. Technically you can use it, but you may see issues with the data.