DNS and Google Dance
Not only Google's index of more than 10,000 servers and the servers are
still in 7 different data centers placed. These data centers are mainly
located in the United States of America (for example, Santa Clara,
California, Herndon, Va.), even in June 2002, the first European in the
Google data center in Zurich, Switzerland on the Internet. It may have
more information centers, which can spread to the whole world.
In order to direct traffic, all these data centers, Google thoeretically
record of all inquiries, then concentrate on the data center. Yet it
clearly inefficient. In fact, data center has its own email address IP
(Internet rooms) and IP address information obtained by means of a system
of management domain name.
Basically, DNS works like this: Internet, data is always between the two
IP addresses. Analysis of the data in the field of IP addresses by name
server DNS. When a user's browser, the local domain name server
configuration, the IP address in connection with the domain name server of
the responsibility to obtain. (DNS is a hierarchical structure of
illustrations, the whole process will be far beyond the scope of this
article ..) IP address, and then you 名称 cache server, so it's not worth
the server name of a reliable partner for each outgoing connection with
the domain.
Name of contact person record in the server space, how long the record
gekasseer by the cache name server. The life domain (TTL) period. Until
the TTL expires, the cache server, the name of the domain name for the
record from the server again. In many cases, TTL set to 1 day. In
contrast, the survival time of the domain www.google.com is only five
minutes. So, the name server may only cache the IP address of Google in
five minutes, and then find the IP address of their behavior.
Each time, contact Google's name server information center only back an IP
address. Thus, searches are always different data centers by changing the
DNS records. On the one hand, DNS records based on a single load the data
center. Thus, Google will use DNS for its simple form of load balancing.
On the other hand, the domain name server cache location affect the
frequency of receiving a single data center IP addresses. This allows the
transmission distance is reduced. To illustrate, DNS records domain
www.google.com, we are here as an example domain name server cache.
As data center, DNS, and Google Dance are related, easy to answer. Google
Dance in the data center do not have a new index, while at the same time.
In reality, the new index is transferred to the data center to another.
When a user asks Google Dance, he may be from the data center, there is
little time to chat message from the data center, it has the new index a
few minutes later, the old results of the index. From a user perspective,
the index work takes place within a few minutes. But, of course, this
process can be reversed, so, Google seems old and new code-breaker.
itches, it would seem, between the old and new index.
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