when i check back links of my website …it shows u have so many back links from these many domains… i am wondering …if we get tons of back links from the same domain does it help for the seo or we need to get back links from different domains ??
yahoo site explorer is the best back link checker.
Since you can not find so many sites to post your link Its better to post in the same one with high pr…
Well said - quality link is more important then quantity.
Search for theme related, high page rank & authority sites.
In the beginning of your Link Building process i would suggest you can do it. But if you already have more than 100 links then you should submit to other websites.
The domain age - site age is an important factor.
Also the frequency of your updates (but you shouldn’t overdo it).
And build for the people not for the SE’s - will get you organic backlinks.
thanks 
i really wanna know this answer… because my competitor has more links but mostly from the same domain . one more question does google even check since how long the website is active and how often do they upload the content ??
Quality plus relevance and high PR - can’t beat that!
These backlink checkers don’t always show all your backlinks, so best to take me with a grain of salt.
Another free backlink checker I just found:
online-utility.org
Keeping track of them is always good. you can use tools for that such as this backlink checker.
Get follow and high PR links from relevant websites and you will do good
Quality, not quantity is the magic answer to your question.
So it’s not a mere matter of number of links, but relevancy and authority that counts. Getting links from the same domain counts just as much as from multiple websites, as long as they are unique and relevant (all other things being equal).