How do I test a software to see if its real time?

What should I use as a benchmark to compare it against?
Is nseindia good for using as a benchmark & is there any other web interface/software that I can use as a benchmark?

I assume that a price at any particular time will always be the same in comparison & even if my software is lagging, I will get the same price at the same price, however I will get it by a delay of few seconds.

Or my software may show different prices at the same time when I compare it against the benchmark?

If you are testing forex prices, just dowload the same platform MT4 from different brokers, and then you will be able to see the latency of the pricing as well as the conditions.
Me I am trading with http://www.traders-trust.com after having checked quite a lot of brokers, but nobody offer prices like them.

this is the only way even is not forex

If you are trading in NSE/BSE, you can check it by placing an order and wait to get it triggered. If you see the price when your order gets triggered, you can assume that your data feed/software is little to no lag. If not, there is...

Heres what I did, I placed an order for buying at market price, the price that I got was different from the market price which means probably my software is lagging.
I have 512 Kbps but I don't think its that less of speed.

I was actually astonished by the difference, it comes to even 1Rs & the value of that stock was Rs 187!
Thats a very high fluctuation.

So there should not be any problem with the real time display but only while placing orders, is that what you are suggesting?
This seems to be the case, i have tried comparing quotes at very specific intervals from my software with NSE, they seem to be the same. However, when I try to buy at market price, i never see the amount that was there when I clicked to conform order.

Don't place market order. If you really want to enter (and no problem with few paise to a rupee) better place a limit order higher/lower (few paise to a rupee than bid/ask). This is what I do. And same goes when exit.

It's not about the bandwidth. I guess, it should be the routing. Our data feeds/order takes a long route to reach the exchange (to and fro). I guess almost all the brokers giving us a second or two delayed quotes/feeds.

No I am suggesting that all the time we are watching few seconds lagging data. Don't take NSE is real and better than the data we see it in your terminal. NSE data updates once in a minute or two. It's not a tick data.