Địa chỉ này không rõ.

Word by word:

• địa chỉ = address
• này = this
• không = not
• rõ = clear, specific, easy to make out

So the structure is literally something like address this not clear.

In Vietnamese, demonstratives usually come after the noun.

So:

• địa chỉ này = this address
• người này = this person
• cuốn sách này = this book

That is normal Vietnamese word order. English puts this before the noun, but Vietnamese usually puts này after it.

Vietnamese often does not use a copula like is/are before adjectives.

So:

• Địa chỉ này không rõ = This address is unclear
• literally: This address not clear

You do not say Địa chỉ này là không rõ in normal Vietnamese.
Using là here would sound unnatural.

không rõ literally means not clear.

Depending on context, it can mean:

• unclear
• not specific
• not easy to read
• not easy to identify
• uncertain

For an address, it could mean:

• the writing is hard to read
• the information is incomplete or vague
• the location is not clearly identified

So không rõ is a useful, slightly broad expression.

No. rõ can mean clear in several ways:

• visually clear: easy to read or see
• mentally clear: easy to understand
• factually clear: definite, certain, specific

Examples:

• Nói rõ hơn đi. = Speak more clearly / explain more clearly.
• Tôi chưa rõ. = I’m not clear on it yet / I don’t fully understand yet.
• Địa chỉ này không rõ. = This address is unclear.

So here it is not only about eyesight; it can also mean the address information is vague.

Because không comes before the adjective or verb when it means not.

So:

• không rõ = not clear
• không đúng = not correct
• không biết = not know

If you say rõ không?, that changes the sentence into a question meaning Is it clear?

Compare:

• Địa chỉ này không rõ. = This address is unclear.
• Địa chỉ này rõ không? = Is this address clear?

Because a classifier is not required here.

Vietnamese classifiers are common, but they are not used in every noun phrase. With many nouns, especially in neutral statements, you can simply say:

• địa chỉ này = this address

You might sometimes hear cái địa chỉ này, but that sounds more colloquial or emphatic, and it is not the most neutral form here.

So địa chỉ này is the normal, standard phrasing.

Usually, địa chỉ most naturally means a physical address or mailing address.

Depending on context, it can also be used for:

• an email address
• a web address
• an address/location in a broader sense

But if there is no extra context, most learners should understand địa chỉ này as this address in the ordinary physical sense.

Yes, it is natural and grammatically correct.

It works well in situations like:

• reading a form
• checking a package
• looking at handwriting
• talking about incomplete address details

For example, if someone sees messy handwriting, they might say:

• Địa chỉ này không rõ.

If you want to be more specific, Vietnamese often adds extra words:

• Địa chỉ này viết không rõ. = This address is written unclearly.
• Địa chỉ này ghi không rõ. = This address is not written clearly.

So the original sentence is fine, but context can make it more precise.

Not usually.

Địa chỉ này không rõ most naturally means the address itself is unclear, not I don’t know this address.

If you want to say I don’t know this address, you would more naturally say something like:

• Tôi không biết địa chỉ này.
• Tôi không rõ địa chỉ này.

Those versions make the speaker the one who is uncertain.
Without tôi, the original sentence describes the address, not the speaker’s knowledge.

They mean different things:

• không rõ = unclear, hard to make out, not specific
• không đúng = incorrect, wrong

So:

• Địa chỉ này không rõ. = The address is unclear.
• Địa chỉ này không đúng. = The address is wrong.

That is an important difference.
An address can be clear but wrong, or unclear but not necessarily wrong.

Yes, but không rõ is usually more natural here.

Compare:

• Địa chỉ này không rõ. = simple, common, natural
• Địa chỉ này không rõ ràng. = also possible, but a bit heavier or more formal

rõ ràng often emphasizes that something is clearly defined or unambiguous.
For a short everyday comment about an address, không rõ is usually the better choice.

A rough learner-friendly guide:

• Địa chỉ ≈ dee-uh chee
• này ≈ nai with a falling tone
• không ≈ khong
• rõ ≈ zaw or yaw, depending on accent, with a creaky rising tone

Important tones:

• địa = heavy/low tone
• chỉ = dipping tone
• này = falling tone
• không = level tone
• rõ = broken/rising tone in northern speech

If you are a beginner, it is better to learn it as a whole chunk:

Địa chỉ này không rõ.

Try to keep the sentence smooth rather than pronouncing each word too separately.