Secrets of Google Domain

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Haha, I am also heading back to the party.

In fact, is not a secret, can only say that I was in the production of Https://github.com/lennylxx/ipv6-hosts summed up the law.

Google is the world's largest internet company, and its sheer scale is reflected in every aspect. One side is its vast global network, and its hard-to-count servers. Some estimate that Google had about 2.38 million servers in early 2013.

Google has built 13 data centers around the world, through its own multi-tier content distribution network (CDN), providing free content and services to users in more than 100 countries around the world.

This article mainly briefly introduces the Google IPV6 address and related domain name.

Google (AS15169) IPv6 address assignment

2001:4860:4000::/36 United States
2404:6800:4000::/36 Australia
2607:f8b0:4000::/36 United States
2800:03f0:4000::/36 Argentina
2a00:1450:4000::/36 Ireland
2c0f:fb50:4000::/36 Kenya


As you can see, Google has applied for almost all of the world's continents with IP segments for its CDN service.

The Asian and Oceania IP segments are registered in Australia, the United States is registered in North America, the countries are registered in Ireland, the countries of South America are Argentina, and Africa is Kenya.

How Google IP segments are managed

Let's take a 2607:f8b0:4000::/36 brief look at how Google IP segments are managed in this example.

This IP segment has a mask of 36 bits, so theoretically the number of available addresses for this IP segment is 2 ^ 92, about 4.95e27.

Such a large number of IP, of course, will not end, but also need a better management method.

Google uses the IATA code of airports near the server deployment location to group servers. The IATA code is a 3-digit English alphabet used to uniquely identify an international airport. For example, the Beijing Capital International Airport code for PEK, Hong Kong International Airport code for HKG and so on.

The meaning of each paragraph of its IPv6 is as follows:

2. The 33-48 number of digits (total 16) indicates the city code, for example, 4000 Dallas, 4007 Los Angeles, 400a Seattle, etc.
   (Note that since all of Google's IP segments have 36-bit masks, all city numbers are 4 prefaced.) )

3. 49-64the first (total 16) is divided into 5 paragraphs, each using a different way, see the table below.

   49-64 Guests	Use
   0-3ff	SN [20]/[6]
   400-7ff	SN [8]
   800-bff	IATA 1e100.net
   C00-fff	XX 1e100.net
   Remaining	Unknown

   As shown in the table:

   • 0-3ffAddress segments are used for SN-encoded domain names, 20 or 6 per set of addresses.
     such as in 4007 Los Angeles (LAX), corresponds to the 1b code a5m7lner .
     (the domain can be *.googlevideo.com *.gvt1.com *.c.youtube.com *.c.docs.google.com *.c.android.clients.google.com. )
   • 400-3ffThe address segment is also used for SN-encoded domain names, with each set of addresses being 8.
     As in Los Angeles, the 402 corresponding code a5m7zu7s .
   • 800-bffThe address segment is used for the IATA encoded address of the 1e100.net domain name, with 32 addresses per group.
     For example 4002 , in Atlanta (ATL), the 802 corresponding encoding atl14s08 .
   • c00-fffThe address segment is used for the two-letter encoded address of the 1e100.net domain name, with 256 addresses per group.
     As in Atlanta, the c01 corresponding code yh .

   For more information on SN-coded domain names and 1e100.net domain names, see the page SN coded domain names, Youtube and 1e100.net.

5. 65-112the first (total 48 digits) is 0.

7. The 113-128 number of bits (a total of 16) indicates the server numbers, corresponding to a separate two-level domain name, please check the hosts file for specific rules.

The four rules above are not so confusing?

Give me a chestnut:

For example dfw06s16-in-x1f.1e100.net , this domain name, this is a typical 1e100.net domain name, its corresponding IPV6 address is 2607:f8b0:4000:800::101f .

• dfwIs the IATA code, representing "Dallas-Fort Worth International Airport", which is Dallas, a city in the northeastern part of the United States Texas, the story of a film in the last period of the "Club of buyers" is happening here. (seems to be pulling away.)
• IPV6 the 3rd paragraph is 4000 , the corresponding is the Dallas.
• -in-Then there is a letter x, which indicates that the next two digits are 16 decimal, and the range of values is 0x00-0x1f, a total of 32 units.
• IPV6 4th Address value range 800-80f, a total of 16 groups of servers, but the number of different locations, the address pool is not fully used.
• The end of the IPV6 address (8th paragraph) is from 1000 to 101f, and corresponds to the domain number.

Another example r1---sn-o097znl7.googlevideo.com of this domain name, which is an SN-encoded domain name, its corresponding IPV6 address is2607:f8b0:4005:4::6

• o09is an IATA-encoded conversion form, which can be obtained by inverting the entire 8-bit SN code, which nuq04s20 is similar to the 1e100.net domain name code in the example above. On nuq behalf of "Malphite Federal Airport", located in the southern part of the city of Mountain View, California, and Mountain View is the location of Google headquarters, check the map you can know that the airport is next to Google headquarters.
• IPV6 the 3rd paragraph 4005 , the corresponding is the mountain city.
• The end of the IPV6 address (8th paragraph) is from 6 to 19, a total of 20, and the domain name number (r1) corresponds.

Refer to the wiki page https://github.com/lennylxx/ipv6-hosts/wiki/sn-domains on how to invert the SN code and get the IATA code address.

If you would like to know more, you can refer to the wiki Https://github.com/lennylxx/ipv6-hosts/wiki and welcome the proposed changes.

You can also view the full 1E100 Server Allocation table and the SN encoded Domain name table. (Scientific internet required)

Secrets of Google Domain