What causes bad RAR with missing blocks when I download?

[Happy Hopping]

Say I download a RAR file from a certain newsgroup, and a few blocks are missing. Would it make a difference if I try it again a few hr. later? Meaning can it cause by bad cable connection?

Or is repairing it via PAR2 the only option?

 

[Whatsisname]

if waiting a few hours or other crap like that was a reliable way of repairing it, there would be no need for par2s in the first place and it wouldn't be customary to include them.

 

[gimp]

99% of the time it's because a file wasn't completely uploaded.

PAR2's are much quicker, anyway.
why wait a couple hours, if you can just repair right then and there?

unless, of course, there are no PAR files provided.

 

[dogbert_2001]

Blocks are missing because the server lost those messages.

Some people have different news service providers to fill in gaps.

 

[Happy Hopping]

there wasn't enough PAR2, in 1 case, there is none. It's unreal that there are people spent x amt. of time to upload the main course, and totally ignore the important of PAR2