subnetting and supernetting

IP address to multiple hosts in the internal network. Through Nat address translation, the reserved IP address is converted into a real IP address when accessing the external network. This ensures that the internal network adopts the TCP/IP protocol while maintaining the uniqueness of the IP address on the Internet. If the internal network is not connected to the Internet, you can actually use any type of address. Otherwise, the connected network address must be unique.

Fast subnet division method subnet division basics: subnetting advantages: 1. reduce network traffic 2. improve Network Performance 3. simplified Management 4. how to Create a subnet that is easy to expand the geographical scope: how to divide subnets? First, you must note that the power of 2: The power of 2 0 to the power of 9 are: 1, 2, 4, 8, 16, 32, 64,128,256, and 512, respectively. It is also worth noting that the subnet division uses the host bi

dividing subnets IP address:: = {Dividing subnets is purely a matter within a unit. The unit is still represented as a network without dividing subnets.From the host number to borrow a number of bits as the subnet number Subnet-id, and the host number Host-id has correspondingly reduced the number of bits.　　Dividing subnets　　When subnets are not divided, the IP address is a level two structure. After subnetting, the IP address becomes a level three s

router, the router knows to forward from a port after parsing the packet, but the router does not know the destination host's MAC address, so it broadcasts the ARP request to get the destination Mac. Suppose the router now does not look for the MAC address, but instead routes the forwarding over IP. After reaching the switch, we assume that the switch is not forwarded based on the mac-port, but instead is forwarded through the ip-port. This hypothetical exchange opportunity learns ip-ports inst

A 1.IP address consists of two fixed fields (network number + host number). After dividing the subnet (the part of the host number is re-divided), to become (network number + subnet number + host number), but the external still appear as a network. such as Class B ip:145.13.0.0. Divided into three subnet 145.13.3.0,145.13.7.0,145.13.21.0. After the datagram (the destination address is 145.13.3.10) arrives at the router, according to the network number, the subnet number, find the destination sub

in the IP address, so the network address of the IP address can be obtained after both "and" operations. The default subnet mask for Class A, Class B, and Class C addresses is fixed: Example, the known IP address is 141.14.72.24, and the subnet mask is 255.255.192.0. Try to find the network address. It should be noted that after the network is crossed, the routing table must contain the following three items: destination network address, subnet mask, and next hop address .

that the default subnet mask for Class A addresses is the 255.0.0.0,b class of 255.255.0.0,c class 255.255.255.0. The following table is the Class C address subnetting and related subnet masks:Number of subnet-subnet-netmask hosts available hosts1 255.255.255.128 128 1262 255.255.255.192 64 623 255.255.255.224 32 304 255.255.255.240 16 145 255.255.255.248 8 66 255.255.255.252 4 2You may notice that the table above is divided by the number of hosts an

longest match when routing is selected is determined by the data structure of the routing table. The priority of routing protocol installation routes depends on the administrative distance value.Visually, depending on the principle of subnetting, you can see which table entry is the "longest match". For example, the routing table has several destination networks (the number behind the slash is the subnet mask length):192.24.96.64/27,192.24.96.96/27,1

The method of dividing subnets is to borrow several bits from the host number of the network as the subnet number, and the host number correspondingly reduces the same number of bits. Before subnetting, the IP address is a level two structure: network number, host number.After dividing the subnet, level two IP address becomes level three IP address within this unit: network number, subnet number, host number.IP Address ={The following is illustrated b

that the default subnet mask for Class A addresses is the 255.0.0.0,b class of 255.255.0.0,c class 255.255.255.0. The following table is the Class C address subnetting and related subnet masks:Number of subnet-subnet-netmask hosts available hosts1 255.255.255.128 128 1262 255.255.255.192 64 623 255.255.255.224 32 304 255.255.255.240 16 145 255.255.255.248 8 66 255.255.255.252 4 2You may notice that the table above is divided by the number of hosts an

array are represented in hexadecimal notation. 16 binary digits can be ":" "." "-" delimited. For example:ETH.DST eq ff:ff:ff:ff:ff:ffAim.data = = 0.1.0.dFDDI.SRC = = Aa-aa-aa-aa-aa-aaEcho.data = = 7aThe IPV4 address can be expressed as a decimal point or as a host name. For example:IP.DST eq www.mit.eduIP.SRC = = 192.168.1.1IPV4 addresses can be compared to numbers, using relationship symbol comparisons: Eq,ne,gt,ge,lt and Le. IPV4 addresses are stored in host order, so you don't have to worry

range notation for IP addresses: https://en.wikipedia.org/wiki/Subnetwork#Subnetting, and the impact of a book "Wireshark network analysis is so simple" introduced by others.There is a book review recommended "graphic TCP/IP Fifth Edition", the first edition of 1994, the Japanese wrote the book, looked at, seemingly and for many years the feeling of almost, still can't see, do not look like also understand, see also is not reach deep and meticulous d

size of the routing table is reduced, but the subnet is opaque to the routers inside the subnet.5. Subnet maskThe partial configuration of any host at boot time is the specified host IP address. In addition to this, you need to know how many bits are used for the subnet number and how many bits are used for the host number. This is determined by the subnet mask during the boot process. The subnet mask is a value with a value of 1, where a bit with a number of 0 is left to the network and subnet

statements show proceslist, adjust MySQL configuration, optimize SQL statement I. Storage, and so on. is not a storage server, such as NFS MFS load and disk IO highThe network foundation must be written, oral, interview:1, the TCP/IP protocol three handshake and four break process. 2. How the HTTP protocol works. 3, LAN machine can not be online troubleshooting. 4, the website opens slowly to troubleshoot (as Operation Dimension). 5, DNS and intelligent DNS resolution 6, OSI7 layer network mode

The so-called Local area network (Network,lan) is used to interconnect a limited range of computers, terminals and external devices in a confined area, such as a laboratory, an office building, or a campus.Under normal circumstances:Less than 10 people, smaller companies generally have less demand for network applications, because of the small number of people, there is no need to partition VLAN (virtual local area network), so the choice of a multi-port switch is sufficient.10 people-100-person

important information data communication; Important information backup and recovery Second level Shockproof wind and rain prevention, Access audit record, Waterproof and moisture-proof, temperature and humidity control; Short-term power reserve; Power supply, communication line isolation + redundant space, access network and core network bandwidth to meet peak business; subnetting, network segment addres

1. you want to download a software from the server, your machine has two network cards eth0 and eth1, the address is configured as follows:Eth0 : 192.168.6.25/24Eth1 : 172.16.101.25/24 default gateway: 192.168.6.1/24 server address:211.138.18.30 At this point, you find that your machine has two routing entries:Destination Gateway genmask Flags MSS Window Irtt Iface211.138.0.0 * 255.255.0.0 U 0 0 0 eth0211.138.16.0 * 255.255.240.0 U 0 0 0 eth1Excuse me: Your machine to the server to downlo

(MAC) address.5. What is the purpose and algorithm of the ARP protocol, and at what level will ARP be used?6. CRC redundancy Check algorithm, anti-code and test algorithm.7. How to achieve transparent transmission.8. Know which data exchange device is used for each layer. (switches, routers, gateways)9. The contents of the routing table.10. Packet forwarding algorithm.The format of IP packets, the meanings of each field in the format should be understood.What is the 12.MTU concept, which is cal

Network Cell number host number The first example: known ip:192.169.20.50 subnet mask: 255.255.255.224 to seek network cell number host number. First, the subnet mask 255.255.255.224 is converted to bits 255.255.255.224:11111111.11111111.11111111.11100000 You can see that the left side of this mask is the same as the Class C default mask, only the fourth section is different from the Class C default mask, that is, the subnet mask grows in the fourth section, so you can think of this 255.255.255

The network IP address "main" is divided into three categories of ABC, the following is the scope of coverage: Class A: 0.0.0.0-127.255.255.255, whose subnet mask is 255.0.0.0 (another way to annotate by subnet mask is/8, which is to convert the subnet mask to binary, from left to 8 1) Class B: 128.0.0.0-191.255.255.255, whose subnet mask is 255.255.0.0 (another way to annotate by subnet mask is/16, which is to convert the subnet mask to binary, from left to 16 1) Class C: 192.0.0.0-223.255.2