Hi,
If you click on the question mark beside Site Status, it gives you Help documentation. Here are the definitions of the two terms:
Your domain score
Provides a measurement of how authoritative Live Search views your domain to be, with 5 green boxes being the highest rating and 5 empty boxes being the lowest. This is based on many of the same factors we use to determine Static Rank, but is not directly comparable.
Your page score
Provides a measurement of how authoritative Live Search views your page to be, with 5 green boxes being the highest rating and 5 empty boxes being the lowest. This is based on many of the same factors we use to determine Static Rank, but is not directly comparable.
So, if you have 1 bar for the domain, it would probably mean that you have a lot of pages with 1 bar. It isn't clear how the domain score is derived all of the page scores. Maybe it's average - when you calculate the average values for all the pages on your website, you get a number close to 1.
... Duane