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Hey there Lisa, Sam from Moz's Help Team here! So something to consider here is how long ago he switched domains/URLs and how long ago those 301 redirects were implemented. Using 301 redirects will redirect your link juice (PA/DA), but you might need to wait a little while (a few index updates) for our crawler to pick up those changes and display the appropriate numbers. If the domain switch was somewhat recent this would explain it. Our Mozscape Index is not a live representation of links. We can store link data for up to 190 days (~6 months) if links are not re-discovered from external linking sites. Generally, most new links that appear in our Index were crawled 3 months ago as this is the current timeframe it takes for us to process new links (and therefore to find and follow/process the 301 redirects). I hope this helps to explain. If you have any other questions, just let us know!