From the articles in the internet , I found that there are two reactions which are being called Lieberman nitroso test .
One is the test of 2 degree amine in which a 2 degree amine is converted to N - nitroso amine using nitrous acid . And this product reacts with phenol to form a red solution which turn blue on addition of alkali . Confirming the presence of 2 degree amine .
And another is the direct reaction of phenol with nitrous acid to form Indo-phenol giving same characteristic red and blue colour .
I am confused and have tried to refer to a lot of sources but with no success .