As a senior Internet users as we all know, the local DNS is very important, it decided in the end you can not access the Internet.
Since the local operator DNS is often criticized by everyone vulnerable to hijacking and other risks, so many people choose public DNS as DNS local Internet use, such as 114DNS, Ali DNS and so on.
However, like to use your public DNS, DNS public know what the drawbacks when online?
Intelligent DNS and CDN Introduction
Complex in China's Internet environment, across regions and between network operators delay is large, so there are intelligent DNS and CDN to solve this problem. My company, Beijing Fastweb is a veteran of the country we CDN service provider; CloudXNS is an intelligent DNS resolution product.
If the Internet site owners the rich and powerful technology cattle, in the operators all over the country and the world are specially deployed independently of the site, then he can be intelligent DNS divisions operators are resolving the domain name into the corresponding sites; if station owners do not have so many points conditions for the deployment, then he can demand through our company completed the CDN.
This is the first application of intelligent DNS and CDN.
Yes, that [accelerated]. Let Beijing Unicom Beijing Unicom users access to (or near the same operator) site, access to Guangdong Telecom Guangdong Telecom (or near the same operator) sites, so as to achieve the purpose of acceleration.
The intelligent scheduling CDN DNS or home users is determined, by the local DNS IP segment belongs to the users.
So, today I want to discuss the shortcomings of the public Internet DNS is this: it goes against the rules of intelligent DNS and CDN to accelerate to a certain extent , become the unhappy.
Local and public DNS DNS
When users visit the Web site, its local DNS request will go to the Web site address, if DNS is not local, it would again request a higher level DNS queries.
Public DNS is a local DNS service provided by a number of companies, usually it will provide users with one or more Anycast IP, but the actual service behind multiple clusters.
When Internet users, client A requests to resolve the address of the cluster, this address is called A DNS entry; intelligent DNS users when the user determines the source address and the IP uses the B cluster DNS database for comparison this address is called DNS B export.
So the online process, the user will get DNS entry to resolve, NS exports to the DNS server will assign intelligent resolution. If the user's DNS entry does not resolve the requested cache will request a higher level DNS queries, ultimately NS request to the server before the user to obtain analytical results.
Then when the user is inconsistent DNS entry and exit and the actual DNS network users, it may lead to intelligent analytical results provided by DNS is not optimal.
Test the sample
Beijing Fastweb official portal www.fastweb.com.cn use Niu Dun cloud security were acceleration and security page, use DNS to resolve the case of operators in the country under normal circumstances as shown in the following figure:
This is the best analytical results through intelligent DNS and CDN two-pronged approach.
For example, Cinderella is the seat of Wuhan, Hubei, when using a local operator DNS and cached, ping www.fastweb.com.cnlatency is as follows:
And I simulated locally pingTaizhou, Zhejiang Niu Dun node 122.226.182.43will delay a little longer to see:
Then the public DNS entrance will not be inconsistent with the actual network do?
Public DNS entry
To Ali DNS 223.5.5.5 for example.
I am a local DNS Ali made a traceroute:
Can be found Ali DNS entry in Hangzhou, Zhejiang, Hubei and my local telecommunications network.
Public DNS export
Just mention when Beijing and colleagues conducted a teleconference this issue, just his PC configuration Ali Public DNS, we let him visit CloudXNS operation and maintenance tool - the local DNS optimization for obtaining export DNS, get feedback as follows:
Beijing Unicom local network, DNS was actually exporting Guangdong Telecom, which is much much bigger than my previous example of the gap between Hubei Telecom and Zhejiang Telecom.
Decoding the Impact of verification
The colleagues were with Ali and operators of the NetEase DNS domain name to do a test comparison.
Ali DNS using the test results:
DNS operators use the test results:
When using operators DNS, pingvalue much faster.
Original: Large column using public DNS disadvantages of the Internet (a)