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I would like to know how exactly my browser knows how to resolve an ip address when I type it directly in my browser.
I know about dns with name resolution, but what if I type xxx.xxx.xxx.xxx ?
I cannot understand what is the followed path to the final server in this precise case.
Doubt that it reaches zny dns server before being redirected, since it is not a name resolution but directly an ip resolution..
Only domain names are resolved to IP addresses, not IP addresses themselves. But I'm afraid your question is not specific enough to be answered concisely here (IMO). And there are loads of online doc about this subject: https://en.wikipedia.org/wiki/IP_address
Then, with more precise questions, you will probably get better answers.
But I just cannot imagine that the root servers do requests/memcache request for all the ip's.
What kind of datacenters would it be ?
Bunch of ram ??
Please excuse me for being a numb, but I just open the eyes.
According to some sources, we talk about 13 clusters of 345 machines overall to handle the whole internet traffic.
The ram needed would not fit in 345 machines. Should we understand that each machine is a memcache shard for each cluster ? and that every cluster has the same datas ?
Then we would have problems with wan, so it is not possible.
Meaning that the informations are replicated 12 other times since every request might not hit the same root server ?
DNS servers that perform the first task are normally managed by your Internet service provider (ISP). As mentioned earlier, the ISP's DNS server is part of the network configuration you get from DHCP as soon as you go online. These servers reside in your ISP's data centers, and they handle requests as follows:
If it has the domain name and IP address in its database, it resolves the name itself.
If it doesn't have the domain name and IP address in its database, it contacts another DNS server on the Internet. It may have to do this multiple times.
If it has to contact another DNS server, it caches the lookup results for a limited time so it can quickly resolve subsequent requests to the same domain name.
If it has no luck finding the domain name after a reasonable search, it returns an error indicating that the name is invalid or doesn't exist.
A is asking for my website.
Either he types www.example.com, then his request will go to his isp then, the isp will ask another dns server.
Or he types my ip address (not likely) and skip the dns step, and, if my ip is dedicated, lands on my website.
Like I said, there are multiple (thousands ? millions?) dns servers. Assuming the requests are really fast between servers, it would still take really long time to get the answer the first time.
Should be -much- more than a minute ?!
In case I run my dns server (SOA) on a new website, the very first time someone looks for my website, his isp will contact many dns hosters/registrars and ask for my dns. My registrar/dns host advertises me, telling the world that my dns is no more hosted by them, but at my nameserver that I put in ns1 ns2. Right ?
1. you can see, it takes less than a second (in general, but sometimes more)
2. not really, your name is registered by your ISP, his DNS will serve your IP. You do not need to have DNS. Also your own DNS will not recognised at all (only if it was registered as "official").
The browser itself recognises valid IP addresses. When it see's one in the URL it does not bother to do a DNS lookup, or in fact what would technicaly be a reverse DNS lookup. The browser goes direct to the IP.
DNS just translates names to numeric IP addresses. Once you've got that number, DNS, just like a phone book, is out of the picture. When you give your browser a valid dotted quad IP address or anything else that can represent a 32-bit (for IPv4) number, it just puts that number into the destination address field of the IP packet and doesn't use DNS at all.