IP Addressing questions

[ccnastudent]

Hi,

I am a Cisco Academy student studying towards CCNA exam.

I would like to know if these are valid IP Addresses to assign to

hosts. If not, please explain(in detail possibly) why.

-150.100.255.255

-175.100.255.18

-195.234.253.0

-100.0.0.23

-188.258.221.176

-127.34.25.189

-224.156.217.73

I have answers for myself but I would like to hear your answers to see

if I understand IP Addressing properly. Thanks very much, I appreciate

your help.

[lgijssel]

I'll accept the challenge, why not!

-150.100.255.255 invalid, class B-broadcast address

-175.100.255.18 valid, class B

-195.234.253.0 invalid, class-C network address

-100.0.0.23 valid, class A

-188.258.221.176 invalid, 2nd number exceeds 255

-127.34.25.189 valid, class A although not adviseable. net 127.0.0.0 is often used as a loopback on several systems (windows, unix)

-224.156.217.73 invalid, class D (multicast)

If there is an incorrect answer, it should be 127.34.25.189. Thats the one that makes me not 100% certain. But strictly applying the rule, why not?

[elpidio]

The IP 150.100.255.255 is a class B broadcast address you cannot assign this one to any host. (Check the host portion 255.255)

The IP 195.234.253.0 is a network address so neither this one.

The 127/8 is reserved by the IANA (Internet Assigned Numbers Authority)

All the others IP NUMBERS are OK.

[7rbowenii]

The other gentlemen provided you answers that seemed apparent, however the validity of these addresses rests on what subnet masks are applied to each network. an ip address ending in 255 is not always invalid nor is every address that ends in 0 a network. if you have the following...

10.0.0.0/23 - 10.0.0.255 and 10.0.1.0 are both valid addresses...

This type of subnet masking is refered to as VLSM or Variable Length Subnet Masking...