Views on the IP address of a net worker
In QQ chat, a netizen lost a net worker's IP address as follows:
Question 57 looks at it this way:
220.17.0.0220.17.7.0 has a total of 8 subnets. Quick calculation: 256-8000248, so the mask is 255.255.248.0.
220.17.0.0Universe 21, item 57: B
Question 57 can also be calculated in this way:
220.17.0.0 converted to binary: 11011100.00010001.00000000.00000000
220.17.7.0 converted to binary: 11011100.00010001.00000111.00000000
Count from left to right, find the different part is the host bit, a total of 3: 8: 11, the network bit has 32-11: 21, so it is 220.17.0. 0: 21
The key is question 58, which is also a strange answer for many people.
First of all, let's talk about the solution in the textbook. because there are 2 ^ 11-2 * 2 ^ 3 = 2032 host addresses, choose A.
Let's talk about the actual usage. Two routers are used to do experiments in Huawei equipment.
R1 and R2 are directly connected by G0UniUniG0. Here are the key configurations:
[R1] dis cur int g0/0/0
[V200R003C00]
#
Interface GigabitEthernet0/0/0
Ip address 220.17.0.255 255.255.248.0
#
Return
[R2-GigabitEthernet0/0/0] dis th
[V200R003C00]
#
Interface GigabitEthernet0/0/0
Ip address 220.17.7.0 255.255.248.0
#
[R1] ping 220.17.7.0
PING 220.17.7.0: 56 data bytes, press CTRL_C to break
Reply from 220.17.7.0: bytes=56 Sequence=1 ttl=255 time=30 ms
Reply from 220.17.7.0: bytes=56 Sequence=2 ttl=255 time=20 ms
Reply from 220.17.7.0: bytes=56 Sequence=3 ttl=255 time=10 ms
Reply from 220.17.7.0: bytes=56 Sequence=4 ttl=255 time=20 ms
Reply from 220.17.7.0: bytes=56 Sequence=5 ttl=255 time=10 ms
-220.17.7.0 ping statistics-
5 packet (s) transmitted
5 packet (s) received
0.005% packet loss
Round-trip min/avg/max = 10-18-30 ms
[R1] dis arp
IP ADDRESS MAC ADDRESS EXPIRE (M) TYPE INTERFACE × × ×-INSTANCE
VLAN/CEVLAN PVC
220.17.0.255 00e0-fcbf-6fae I-GE0/0/0
220.17.7.0 00e0-fcbb-4fa6 19 Dmuri 0 GE0/0/0
Total:2 Dynamic:1 Static:0 Interface:1
Although from the textbook point of view, although they are class C addresses, network addresses and broadcast addresses, in dis arp, routers think they are on the same network segment, and you can see that they communicate with each other.
Throw a brick to attract jade here.
