asked in 教育與參考考試 · 1 decade ago

ccna考題請教

各位大大,請問下面這題,他的答案是acf 可是我不太懂c選項的意思(英文程度不太好),可否請大大幫忙解釋c的意思,其它的我都看的懂,就只有c不太了他在說什麼。

Which of the following are true regarding a network using a subnet mask of

255.255.248.0? (Choose three)

A. It corresponds to a Class A address with 13 bits borrowed.

B. It corresponds to a Class B address with 4 bits borrowed.

C. The network address of the last subnet will have 248 in the 3rd octet.

D. The first 21 bits make the host portion of the address.

E. This subnet mask allows for 16 total subnets to be created.

F. The subnetwork numbers will be in multiples of 8.

Answer: A, C, F

Explanation:

This subnet mask includes the first 5 bits within the third octet, so for a class A address 13

bits will be used for the mask (8 bits in the second octet plus 5 in the third).

Since the first 5 bits are used in this octet, that means that remaining 3 bits in this octet

will be available for hosts, so each network will be a factor of 8, making the last available subnet with a .248 in the third octet. 這一段是它的解釋,可是我還是不太了c的意思~

1 Answer

Rating
  • 雲友
    Lv 4
    1 decade ago
    Favorite Answer

    IP位址分為4個區域,每個區域由8個 bit 組成,一般稱作1個 Byte,也就是 8 bits = 1 Byte ,但用在 IP 上,不叫 Byte ,而是稱作 Octet,題目中4個數字是 255.255.248.0 ,表示網路號碼用前面3個 Octet 來識別,所以它說 248 在第三個 Octet 。

    Source(s): 自己
Still have questions? Get your answers by asking now.