OpenDNS is a Domain Name System (DNS) resolution service. OpenDNS extends DNS adding features such as misspelling correction, phishing protection, and optional content filtering. It provides an ad-supported service[2][3] "showing relevant ads when we [show] search results" and a paid advertisement-free service.
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[edit]Services
[edit]DNS
OpenDNS offers DNS resolution as an alternative to using Internet service providers' DNS servers. There are OpenDNS servers in strategic locations, and they also employ a large cache of the domain names..[citation needed] OpenDNS has adopted and supports DNSCurve.[4]
OpenDNS provides the following recursive nameserver addresses[5] for public use, mapped to the nearest operational server location byanycast routing:
- 208.67.222.222 (resolver1.opendns.com)
- 208.67.220.220 (resolver2.opendns.com)
- 208.67.222.220 [5]
- 208.67.220.222 [5]
- 2620:0:ccc::2
- 2620:0:ccd::2
Other features include a phishing filter, domain blocking and typo correction (for example, typing "example.og" instead of "example.org"). OpenDNS maintains a list of malicious sites and blocks access to them when a user tries to access them through their service. OpenDNS also run a service called PhishTank for users to submit and review suspected phishing sites.
The name OpenDNS refers to the DNS concept of being open, where queries from any source are accepted. It is not related to open source software; the service is based on closed-source software.[7]
OpenDNS earns a portion of its revenue by resolving a domain name to an OpenDNS server when the name is not otherwise defined in DNS. This has the effect that if a user types a non-existent name in a URL in a web browser, the user sees an OpenDNS search page. Advertisers pay OpenDNS to have advertisements for their sites on this page. This behavior is similar to VeriSign's previous Site Finder or the redirects many ISP's place on their own DNS servers, but it is a service provided only at users' request.[8] OpenDNS says that the advertising revenue pays for the free customized DNS service.[9]
As of March 2010 OpenDNS said that it handled over 20 billion DNS requests daily, with over 26 billion delivered on 21 April, 2010.[10]
OpenDNS may have negligible performance gain, [11] but may process queries more quickly than an ISP with slow DNS servers.[12] DNS query results are sometimes cached by routers (e.g. typically local ISPs queries may be cached by ISPs home routers), the local operating system or applications, so speeds may not be noticeable with every request but only with requests that are not stored in a local cache.
[edit]DNS rebinding protection
To provide protection against DNS rebinding, private IP addresses can be (optionally) filtered out of DNS responses.[13]
[edit]Domain-blocking
On May 13, 2007, OpenDNS launched a domain-blocking service to block or filter web sites visited based upon categories, allowing control over the type of sites that may be accessed. The filters can be overridden through individually managed blacklists and whitelists. In 2008 OpenDNS changed from a closed list of blocked domains to a community-driven list allowing subscribers to suggest sites for blocking; if enough subscribers (the number has not been disclosed) concur with the categorization of the site it is added to the appropriate category for blocking. As of 2011 there were over 50 categories. The basic OpenDNS service does not require users to register, but using the block/filter feature requires registering and logging in.[14]
[edit]FamilyShield
OpenDNS also provides the following recursive nameserver addresses as part of their FamilyShield[15] parental controls which block pornography, proxy servers, phishing sites and some malware:
- 208.67.222.123
- 208.67.220.123
[edit]DNSCrypt
DNSCrypt encrypts DNS traffic between the user's computer and the OpenDNS name servers for Windows, Linux, Mac OS X and iPhone.[16]
[edit]Dynamic DNS
On December 3, 2007, OpenDNS began offering the free DNS-O-Matic service to provide a method of sending dynamic DNS (DDNS) updates to several DDNS providers using DynDNS's update API.[17]
[edit]
On October 21, 2009, OpenDNS launched OpenDNS premium services, for small businesses and enterprises with advanced needs. For a charge, the service offers ad-free result pages, increased reporting and block features, and other services. Pricing for the Enterprise version starts at $2000 per year.[18] The deluxe version, more customisable than the free-of-charge basic version and free of advertisements, costs $19.95 per year for families.[18]
Starting March 15, 2012, OpenDNS Enterprise for Small Business appears to start at $1,500 based on a forum posting that refers to emails received by current subscribers. [19]
Reference : http://en.wikipedia.org/wiki/OpenDNS
