What are the first address & Last Address In This Block

In a block of addresses, we know the IP address of one host is 25.34.12.56/16. What are the first address (network address) and the last address (limited broadcast address) in this block please explain ??

Instead of asking question, sit back and relax and wait for answers to be thrown on your lap, you could also google 1 second and have the answer.

I understand you have started your CCNA, very good, but don't think you will get there by sitting back and have us as your teacher for EVERY subject, sorry if I am a bit rude, but I just 'hate' people don't want to put ANY effort in research.

Under Networking >> General >> Subnetting you can find your answers.

If you still don't understand the basics, feel free to ask a question and tell us how you THINK things are and what you don't understand.


For all other people, correct me if I'm too rude or whatever, it's just.. just

I agree entirely with Chojin. It's similar to the saying:

"Tell me and I will forget
Show me and I might remember
Involve me and I will understand"

There's no point anyone here just feeding answers unless there's an indication of some understanding of basic features and previous research. I'm far from an expert but have had several very useful responses to questions that I have posted here and I hope that they demonstrated the qualities that I have recommended.

Two good posts above. I don't want to labour the point and members should never have trepidation about posting any questions but the quality of answer will most likely depend on the quality of the question - you can tell when someone has a genuine interest in the topic.

Also, finding stuff for yourself is a such a vital skill in real work that members should be encouraged to figure as much as they can out for themselves. I think it would make a great CCNA exam question too, answer a question on an obscure unknown technology by searching the Cisco KB and a RFC (:

In a block of addresses, we know the IP address of one host is 25.34.12.56/16. What are the first address (network address) and the last address (limited broadcast address) in this block please explain ??

I'm believe you've taken note of members' comments above so I'll give your question ago.

first useable address: 25.34.0.1
last useable address: 25.34.255.254
broadcast address: 25.34.255.255

IP calculators are quite useful for such but there wont be any in the CCNA exams (assuming you're studying for it)...

Brief explanation:
Since it's a /16 address, the last 2 octets (12 and 56) become 'irrelevant' so just replace them with zeros (25.34.0.0). This is the network address/ID. The first usable address is as stated above.
Next is to work out the broadcast address, reduce the last octet (255 in this case) by 1 and you get the last useable ID (254).

A good tip to remember is that:
> Network addresses are always EVEN
> first useable address are always ODD
> last useable addresses are always EVEN
> broadcast addresses are always ODD numbers

This can be useful for elimination in the test.

Hope it helps![/b]

I'm believe you've taken note of members' comments above so I'll give your question ago.

Since the "I have a question, don't wanna know shit about it, just need answers" question.. haven't heared ANYTHING from him/her... I Just hope your belief is right .