All I can say apart from what GKaiseril has mentioned in Post 1 is every PDF created from/within Adobe Acrobat meets this standard. If it's a third party PDF, you can try refrying it by printing to Adobe PDF printer and getting a new one created.
You can read more on this blog by James C. King. It's very informative.
for showing a new pre-flight feature in acrobat it sound intresting as i was not aware of it at all and its useful too
And Sandeep your mention blog link is intresting too
I had find a new link that showing that adobe Supplement to ISO 32000-1 and it is useful too sharing link with you.
ISO 32000-1 is nothing to do with PDF/A - it is the core standard for the PDF/1.7 document format. PDF/A is covered by ISO 19005-1.
Preflight can run a number of checks but there is no easy way to verify compliance with PDF/1.7 as a whole. You can try the "Report PDF Syntax Issues" profile in Preflight but that does not guarantee to detect non-compliance, only the most common things which will break the document.
Creating your PDF files using a standards-compliant application such as Adobe Acrobat is by far the best option - I never recommend refrying a PDF unless there is a specific necessity to do so and the file is only destined for hardcopy print, as it will break pretty much everything (accessibility tags, scripts, forms, links, media, layers, color spaces, certificates, etc.).
Because it's not easy to verify, and Acrobat always produces standards-compliant files, many commercial printers and publishers insist on "Adobe PDFs" rather than generic ones, and will reject files that have been created with third-party software.