well when its about SEO we hear about HTTP requests and DNS requests. As far as HTTP requests are concerned they are number of requests sent outside the site (external links) so if they are more in numbers it means that it will take more time to load the site. BUT that's where comes DNS into talk, i guess the number of requests of external files from different servers is DNS.
Here DNS requests would be all these providers (flickr,picassa,code google, own hosting) so if they increase the page load time increases too.
Now my questions are:
1- Do DNS really effect?
2- How to get to know which server is good for us and which one is bad?
4- Too many request from same DNS can make it slow, NOW HOW TO FIND OUT as which one is going to get slow and which one is not?
5- What is the limit to number of requests from same DNS (how many links should be from one DNS)?