dns lookup VS HTTP Parallel downloads

Question

HTTP 1.1 allows 2 connections per host name. On the other hand, yahoo performance rules suggest to reduce the number of DNS look ups.

how does one balance this? thanks

Answer 1

This article (unfortunatly, quite old, as it's from 2007 ; but it still seems to be reasonable), might help you : Performance Research, Part 4: Maximizing Parallel Downloads in the Carpool Lane ; quoting the last paragraph :

Our rule of thumb is to increase the number of parallel downloads by using at least two, but no more than four hostnames. Once again, this underscores the number one rule for improving response times: reduce the number of components in the page.

But read the article : there are some other interesting reflexions and resutls of experimentations.