Non ho nessun dubbio sul risultato.

Yes, it is a double negative by English standards, but in Italian this is completely normal.

Non ho nessun dubbio literally looks like I do not have no doubt, but in correct Italian it means I have no doubt.

A useful pattern to remember is:

• non + verb + nessun/niente/mai...

Examples:

• Non ho nessun problema. = I have no problem.
• Non vedo nessuno. = I don’t see anyone.
• Non dico mai questo. = I never say this.

So in Italian, non often works together with another negative word.

Because nessun is the form usually used before a singular noun.

Here, dubbio is a masculine singular noun, so Italian says:

• nessun dubbio

This works like:

• nessun problema
• nessun libro
• nessuna idea (feminine singular)

You may also see nessuno, but that form is used mainly:

1. By itself as a pronoun
   
   • Nessuno è arrivato. = No one arrived.
2. Before certain masculine nouns beginning with special consonant sounds
   
   • nessuno studente
   • nessuno psicologo

Since dubbio does not begin with one of those sounds, nessun dubbio is correct.

Italian often uses the singular where English prefers the plural.

So:

• non ho nessun dubbio = literally I don’t have any doubt
• natural English: I have no doubt / I have no doubts

Both ideas are fine in English, but Italian strongly prefers the singular noun here.

This is very common with words like:

• avere fame = to be hungry
• avere paura = to be afraid
• non avere nessun dubbio = to have no doubt

So don’t try to match English number word-for-word.

Ho is the present tense of avere = to have.

It is:

• io ho = I have

So:

• Non ho = I do not have / I don’t have

Full present tense of avere:

• io ho
• tu hai
• lui/lei ha
• noi abbiamo
• voi avete
• loro hanno

In this sentence, ho is a main verb, not an auxiliary.

Sul is a contraction of:

• su + il = sul

Here:

• su = on, about, over, concerning
• il risultato = the result

So sul risultato means something like:

• about the result
• regarding the result
• sometimes literally on the result, depending on context

Italian often contracts preposition + article:

• su + il = sul
• su + lo = sullo
• su + la = sulla
• su + i = sui
• su + gli = sugli
• su + le = sulle

Because avere dubbi su qualcosa is a common Italian pattern.

You typically say:

• avere dubbi su = to have doubts about

So:

• Ho dubbi sul piano.
• Abbiamo dubbi sulla decisione.

Other expressions can also work in some contexts, such as:

• riguardo al risultato
• circa il risultato

But su is the most direct and natural choice after dubbi in many everyday sentences.

Yes. That is also correct and very natural.

Compare:

• Non ho dubbi sul risultato.
• Non ho nessun dubbio sul risultato.

Both mean essentially the same thing: I have no doubt(s) about the result.

The version with nessun can sound a little more emphatic, because it reinforces the negation.

You may also hear:

• Non ho alcun dubbio sul risultato.

That is slightly more formal or polished than nessun, but also very common.

Both can mean no / any in negative sentences.

Compare:

• Non ho nessun dubbio.
• Non ho alcun dubbio.

Both are correct and mean I have no doubt.

General difference:

• nessun = very common, everyday
• alcun = often a bit more formal or elegant

Without non, these usually do not mean the same thing in ordinary modern Italian. In this sentence, because non is present, both are fine.

No, that would not be natural standard Italian.

The normal order is:

• Non ho nessun dubbio sul risultato.

This follows the usual pattern:

• non + verb + object + complement

You can move parts around for emphasis in special contexts, but beginners should stick with the standard order.

Natural alternatives include:

• Non ho dubbi sul risultato.
• Sul risultato non ho nessun dubbio.
  This is possible if you want to emphasize about the result.

But Nessun dubbio non ho... is not the normal way to say it.

Dubbio is a masculine singular noun meaning doubt.

In this sentence:

• nessun modifies dubbio
• together they form the direct object of ho

Structure:

• Non = negation
• ho = verb
• nessun dubbio = direct object
• sul risultato = prepositional phrase giving the topic

So the sentence is built very regularly.

Normally, no. Nessun usually comes before the noun:

• nessun dubbio
• nessun problema
• nessuna domanda

If it stands alone, then it acts as a pronoun:

• Non ho visto nessuno. = I didn’t see anyone.
• Nessuno sa la risposta. = No one knows the answer.

So in this sentence, before the noun is exactly where it should be.

Yes, very easily. This sentence is a useful model.

Pattern:

• Non ho nessun dubbio su + noun

Examples:

• Non ho nessun dubbio sulla tua sincerità.
• Non ho nessun dubbio sul piano.
• Non ho nessun dubbio sulla risposta.
• Non ho nessun dubbio sui dati.

Just remember that su changes depending on the article:

• sul = su + il
• sulla = su + la
• sui = su + i
• sugli = su + gli
• sulle = su + le

It is basically neutral and natural in both speech and writing.

• Non ho nessun dubbio sul risultato. sounds normal and clear.
• Non ho alcun dubbio sul risultato. sounds a little more formal.
• Non ho dubbi sul risultato. sounds very natural and slightly simpler.

So the original sentence is a good standard everyday sentence.