CCNA Learning must be remembered

CCNA Learning must be remembered

--Hundred dishes

In the study Shehiren "Computer network" over the name, found that there are some very important but not dissected knowledge points in the book, perhaps in the new version of the content will be constantly updated, but in any case, we can often look at these points of knowledge, strengthen memory. After continuous learning, bloggers will occasionally add something else-something they think is useful to novices.

1. In learning to divide the subnet that piece, it may be easy for everyone to ignore enable 0 subnets: (Enable command IP Subnet-zero)

If you configure the routing interface with the address 192.168.10.6 255.255.255.248, the following error message appears:

"Bad mask/29 for address 192.168.10.6"

This indicates that the command IP Subnet-zero is not enabled. The address used here is Subnet 0 (192.168.10.0/29).

2. Some special addresses to remember:

127.0.0.1 Loopback test Address, you can test the local network card is normal;

Private address: Class A 10.0.0.0--10.255.255.255

Class B 172.16.0.0--172.31.255.255

Class C 192.168.0.0--192.168.255.255

Private addresses are not routable in the Internet. That is, you configure the scope of the private address after the host is unable to access the Internet;

The multicast address is Class D (244.0.0.0-239.255.255.255); Class E is used for research.

All 0 network addresses are reserved for specifying the default route (0.0.0.0 0.0.0.0)

3. Default Subnet mask

Class A: 255.0.0.0

Class B: 255.255.0.0

Class C: 255.255.255.0

For Class A addresses, the first byte must be 255, followed by no specific requirements;

For Class B addresses, one or two bytes must be 255.255, followed by no specific requirements;

For a Class C address, the first must be 255.255.255, followed by no specific requirements, as long as the mask format is OK.

This article is from the "Hundred Dishes" blog, please be sure to keep this source http://powersource.blog.51cto.com/11364294/1783190

CCNA Learning must be remembered