I would like to know the network part and host part of the IP address.
The IP address specified in the DNS A record does not know the class, does not have a subnet mask and does not have a CIDR.Where is the network part?
How do I know if I want to know the network department when I use nslookup, such as ↓ or Rails log IP address in a log of s or Rails?I don't think I know because I haven't been given any information about where the network is.
$nslookup google.com
Server: 192.168.11.1
Address: 192.168.11.1#53
Non-authoritative answer:
Name: google.com
Address: 172.217.161.238
In addition to the previous question, I would appreciate it if you could explain this as well.
whois 172.217.161.238
Then, I was told that I could understand the CIDR notation.I would also like to know, but how do you want CIDR notation from IP address only?
Check the configuration directly on the server to which 172.217.161.238 is assigned, check the configuration of the network to which the 172.217.161.238 server is connected, i.e., unless you say you are a Google server or network administrator.
The only information that can be seen from the outside is that Google is assigned an IP address in the range of 172.217.0.0/16.Google does not always use /16 as /16.You may be using it separated by 172.217.0.0/24, 172.217.1.0/24, ... and /24; or you may be using only two octets, which are further divided into 172.217.2.0/25, 172.217.2.128/25.It's up to Google to split it up and it's up to Google's networking staff to figure out what to do to use IP addresses efficiently.It could be a very small 172.217.161.238/30 or 172.217.161.238/16 as it is.
Also, it can be narrowed down to some extent from routing route information that flows through BGP on the Internet.For example, if 172.217.161.0/24 were advertised as if a router managed by Google was the destination, it would be narrower than /24 but not necessarily /24.It may be further divided into /25 or /26 from the routers that Google manages.However, there is no need to inform third parties on the Internet of this information, so it will not be promoted through BGP.From now on, you won't know until you actually ask Google, but for security reasons, you basically don't give details of your network configuration to third parties.
How do you want CIDR notation from IP addresses only?
The response message from the WHOIS server is not required by any algorithm, and CIDR is listed directly (and can be expected).
NetRange: 172.217.0.0-172.217.255.255
CIDR: 172.217.0.0/16
NetName:GOOGLE
[...]
Note: https://www.nic.ad.jp/ja/newsletter/No34/0800.html
The WHOIS protocol is a very simple protocol that simply specifies that a server running on TCP port 43 will respond to textual requests from clients, and there is no answer format or other provision.Therefore, WHOIS specifications have been established and operated for each information management policy of the organization providing the service.That's why each WHOIS server has a different format for the answer.
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