You just follow a random link, that looks like a web 2.0 properties and then look into the backlinks for the particular tier.
But use your time wisely. Spending hours on tracking down the whole pattern for a competitors linknetwork, does not create any value for your site!
The most important thing, is just to get a quick overview:
How many links?
What kind of links?
The quality of links?
Does it looks like your competitor use a lot of time on his/her SEO work?
And then make a linkstrategy for your own site and take action. Don't spend to much time, wondering why your competitor rank better than you. Use your time on your own onsite and offsite SEO.