This question excludes 'default' used in court or 'a default' for an indefinite future (e.g. setting a default option). My question pertains to circumstances where the context behind the question or sentence is known and 'default' means using one option over other options. I found that sometimes people use indefinite articles, but I could not figure out the reason behind it.
For example, how would you interpret these three questions differently?
1) "Is this a default behavior?"
2) "Is this the default behavior?"
3) "Is this default behavior?"
What if I were to drop the the noun? Is that going to change anything?