Typically, such caching DNS servers, also called DNS caches, also implement the recursive algorithm necessary to resolve a given name starting with the DNS root through to the authoritative name servers of the queried domain.

In addition, many home networking routers implement DNS caches and recursors to improve efficiency in the local network.

The time for which a resolver caches a DNS response is determined by a value called the time to live ( TTL ) associated with every record.

As a noteworthy consequence of this distributed and caching architecture, changes to DNS records do not propagate throughout the network immediately, but require all caches to expire and refresh after the TTL.

It then returns its results to the DNS resolver ; assuming it has found a result, the resolver duly caches that result for future use, and hands the result back to the software which initiated the request.

Caching name servers, also called DNS caches, store DNS query results for a period of time determined in the configuration ( time-to-live ) of each domain-name record.

These patches worked by modifying the DNS lookup WinMX uses to find peer caches.

* Items that expire with time: Some caches keep information that expires ( e. g. a news cache, a DNS cache, or a web browser cache ).

The DNS Client service itself communicates with DNS servers, and caches the results that it receives.

When a DNS server has received such non-authentic data and caches it for performance optimization, it is considered poisoned, supplying the non-authentic data to the clients of the server.

To improve efficiency, reduce DNS traffic across the Internet, and increase performance in end-user applications, the Domain Name System supports DNS cache servers which store DNS query results for a period of time determined in the configuration ( time-to-live ) of the domain name record in question.

DNS servers are generally deployed in an organization's network to improve resolution response performance by caching previously obtained query results.

( Some newer protocols, such as Kerberos and Active Directory use DNS SRV records to identify services by name, which is much closer to the AppleTalk model.

Domains are identified by their DNS name structure, the namespace.

An authoritative name server is a name server that gives answers that have been configured by an original source, for example, the domain administrator or by dynamic DNS methods, in contrast to answers that were obtained via a regular DNS query to another name server.

* A recursive query is one for which the DNS server will fully answer the query ( or give an error ) by querying other name servers as needed.

The DNS Resolution Process reduces the load on individual servers by caching DNS request records for a period of time after a response.

The TTL is set by the administrator of the DNS server handing out the authoritative response.

When the DNS resolver gets a PTR ( reverse-lookup ) request, it begins by querying the root servers ( which point to The American Registry For Internet Numbers ' ( ARIN's ) servers for the < tt > 208. in-addr. arpa </ tt > zone ).

A number of large ISPs have configured their DNS servers to violate rules ( presumably to allow them to run on less-expensive hardware than a fully compliant resolver ), such as by disobeying TTLs, or by indicating that a domain name does not exist just because one of its name servers does not respond.

Internet Explorer represents a notable exception: versions up to IE 3. x cache DNS records for 24 hours by default.

DNS queries consist of a single UDP request from the client followed by a single UDP reply from the server.

Most of the features of BIND 9 were funded by UNIX vendors who wanted to ensure that BIND stayed competitive with Microsoft's DNS offerings ; the DNSSEC features were funded by the US military, which regarded DNS security as important.

* DNS and BIND, Fifth Edition by Paul Albitz, Cricket Liu.

The djbdns software package is a DNS implementation created by Daniel J. Bernstein due to his frustrations with repeated BIND security holes.

In addition to helping develop TCP / IP and the Domain Name System ( DNS ), ISI contributed to the Net by editing the " Request for Comments " ( RFC ) series, the written record of the emerging network's technical structure and operation, from 1977 through 2009.

The Green Paper proposed for discussion a variety of issues relating to DNS management including private sector creation of a new not-for-profit corporation ( the " new corporation ") managed by a globally and functionally representative Board of Directors.

The naming scheme used on Janet ( Janet NRS ) had similarities to the Internet's Domain Name System, but with domains specified in big-endian format rather than the little-endian style used by DNS.

In practice caching is used in DNS servers to overcome this problem, and as a result, root nameservers actually are involved with very little of the total traffic.

With blackholing, all the traffic to the attacked DNS or IP address is sent to a " black hole " ( null interface, non-existent server, ...).

High-level root nameservers, DNS, and routers direct the traffic on the internet.

This way, when a server is down, its DNS will not respond and the web service does not receive any traffic.

If the line to one server is congested, the unreliability of DNS ensures less HTTP traffic reaches that server.

It has a wide variety of uses, from speeding up a web server by caching repeated requests ; to caching web, DNS and other computer network lookups for a group of people sharing network resources ; to aiding security by filtering traffic.

Neustar offers internal and external managed DNS services that play a role in directing and managing traffic on the Internet, manages the authoritative directories for the. us and. biz Internet domains, and acts as the worldwide " registry gateway " for China's. cn and Taiwan's. tw Internet domains outside of these two countries.

* that the Site Finder service assumed that all DNS traffic was caused by Web clients, ignoring the fact that DNS is used by other applications such as network printer drivers, FTP software and dedicated communications applications.

No statement by VeriSign in support of Site Finder even acknowledged the existence of DNS traffic not caused by web clients, although they published implementation details which mentioned this traffic.

In addition to the name itself, users can opt to forward their web traffic using HTML frames and their email traffic, with a maximum of 250 addresses per user log in, or use full DNS, either via their own or third-party servers, or by using Dot TK's servers.

DNS and firewall records must be updated to redirect traffic to a different / 48 subnet.

This works in most cases, but has the disadvantage that DNS and firewall records must be updated to redirect traffic to the correct set of IP addresses if one of the links goes down.

Pharming occurs when a hacker redirects website traffic from a legitimate website to the hacker's fraudulent website by exploiting vulnerabilities in the Domain Name System ( DNS ).

All providers but one require a DNS change, wherein all web traffic is routed through the WAF where it is inspected and threats are thwarted.

As of early 2005, PowerDNS, in combination with the bind and geo backends, is used by Wikimedia to handle all DNS traffic.

In February 2002, the DigiServe DNS servers were hacked by pro-democracy activists, which resulted in the traffic to all. mm domain names including www. gov. mm being redirected to a website demanding the release of famous student leader Min Ko Naing for a period of three days.