23 Facts About DNS


The DNS can be quickly and transparently updated, allowing a service's location on the network to change without affecting the end users, who continue to use the same hostname.

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An important and ubiquitous function of the DNS is its central role in distributed Internet services such as cloud services and content delivery networks.

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The key functionality of the DNS exploited here is that different users can simultaneously receive different translations for the same domain name, a key point of divergence from a traditional phone-book view of the DNS.

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DNS reflects the structure of administrative responsibility in the Internet.

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DNS can be partitioned according to class where the separate classes can be thought of as an array of parallel namespace trees.

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Limited set of ASCII characters permitted in the DNS prevented the representation of names and words of many languages in their native alphabets or scripts.

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Typically, such caching DNS servers 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.

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DNS resolvers are classified by a variety of query methods, such as recursive, non-recursive, and iterative.

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The resolver, or another DNS server acting recursively on behalf of the resolver, negotiates use of recursive service using bits in the query headers.

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Results obtained from a DNS request are always associated with the time to live, an expiration time after which the results must be discarded or refreshed.

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Reverse DNS lookup is a query of the DNS for domain names when the IP address is known.

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DNS serves other purposes in addition to translating names to IP addresses.

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For instance, mail transfer agents use DNS to find the best mail server to deliver e-mail: An MX record provides a mapping between a domain and a mail exchanger; this can provide an additional layer of fault tolerance and load distribution.

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DNS is used for efficient storage and distribution of IP addresses of blacklisted email hosts.

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DNS protocol uses two types of DNS messages, queries and replies; both have the same format.

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Use of DNS-over-UDP is limited by, among other things, its lack of transport-layer encryption, authentication, reliable delivery, and message length.

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An IETF standard for encrypted DNS emerged in 2016, utilizing standard Transport Layer Security to protect the entire connection, rather than just the DNS payload.

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Oblivious DNS was invented and implemented by researchers at Princeton University and the University of Chicago as an extension to unencrypted DNS, before DoH itself was standardized and widely deployed.

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The privacy gains of Oblivious DNS can be garnered through the use of the preexisting Tor network of ingress and egress nodes, paired with the transport-layer encryption provided by TLS.

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CLASS of a record is set to IN for common DNS records involving Internet hostnames, servers, or IP addresses.

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DNS records belonging to wildcard domain names specify rules for generating resource records within a single DNS zone by substituting whole labels with matching components of the query name, including any specified descendants.

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Original DNS protocol had limited provisions for extension with new features.

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In 1999, Paul Vixie published in RFC 2671 an extension mechanism, called Extension Mechanisms for DNS that introduced optional protocol elements without increasing overhead when not in use.

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