Device isn't eligible for the requested build?

Trying to update my iphone and this message keeps popping up device isn't eligible for the request build? I tried fixing it by going to hosts heres what my host file looks like

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting. Do not change this entry.
##
127.0.0.1 localhost
255.255.255.255 broadcasthost:1 localhost
fe80:1%lo0 localhost
# 74.208.10.249

if this is not how is should be someone copy and paste theirs as an answer 10 points

Your question is way too vague. What is the Model number of your iPhone, how old is it, and what version of iOS is currently running on it?

Apple's latest mainstream Mobile Operating System, iOS 6, only runs on newer iPhone Models. And your iOS version may be even older, hence the cryptic message.

And I do hope you are NOT trying to install iOS 7, it is BETA ONLY (buggy, and unstable), and should be avoided like the Plague, until the Final pre-release later this year.

I can't copy and paste mine, because all hosts are different. The reason why iTunes says this is because probably, your iPhone is too old for the current firmware which you are trying to update to. Like let's say you are trying to update an iPhone 3GS to IOS 6. X.X. It will say that because IOS 6 does not support the iPhone 3GS.