Internet what is dns

When a query is sent by a device, domain name servers and resolvers step in. They ensure that the query gets a response from the relevant record.

Queries, also known as DNS lookups, are happening all the time. Some of these activities take place within your network—these internal DNS queries never make it to the public internet. On the other hand, for external websites, queries are sent outside of your network and rely on external servers for resolution. There are two types of DNS servers: recursive resolvers and authoritative nameservers. The latter includes root servers as well as top-level domain TLD servers. A TLD is the last part of a domain, such as.

Authoritative nameservers are also sometimes referred to as authoritative DNS servers. An important note: This information will often be cached locally inside the device or somewhere in the DNS server infrastructure.

As a result, cached information circumvents further steps and delivers the record. Certainly, servers cache responses to resolve queries more efficiently. Most stub resolvers are also designed to cache records for a while, known as the time to live TTL.

Once the TTL expires, the server needs to resolve the query again. Many scenarios require a lookup. Here are eight basic steps for a very common one, using a web browser:. The domain name system is also used for various types of service discovery. For example, finding the appropriate mail server for an email address or the nearest Active Directory server. A specific entity or administrator can manage each zone.

This technique provides admins with more control over specific components, such as authoritative name servers. A number of zones can exist on the same server. Furthermore, each zone typically exists on multiple servers, using automatic replication to keep the copies in sync. Zones are separated at the dots in a domain name. This allows the TLD name server to delegate a subzone to a child domain e.

It is often used as a shorthand acronym to describe integrating three core components of networking into one centralized management solution. Bringing these core services together into a BlueCat platform solution can transform network management. Building out DNS services requires a layered approach to your architecture. A DNS query can be one of the following:. In a recursive DNS query, a DNS client will reach out to a server, which will in turn make upstream requests for the domain in question until a result is found.

The only set rule for a recursive query is that a result must be returned, if there is one. There can be a single or dozens of recursions.

The initial server or even the local DNS client may have a result already cached. A time-to-live TTL value governs how long one of these results can be cached; once the TTL has been reached, the client or server will need to look upstream for the results.

The requester will continue this iterative process until it finds an answer or times out. As stated already, DNS is a distributed system, meaning that servers all over the world work together to maintain and deliver DNS records. Different types of servers have different roles within the overall system:. Sometimes called a recursive resolver, a DNS recursor receives queries from DNS clients, responds if a hit is available in cache, or reaches out to a nameserver further up the chain.

Recursors are often run by Internet Service Providers, but its easy to change the DNS configuration of a computer to point to another source for performance, security, or privacy reasons. As the name implies, root servers are the foundation from which the entire DNS infrastructure grows. TLD Name Servers are second in importance only to the root servers, as they know where to turn for answers about any domain within a given TLD.

When you search for www. The authoritative name server is the final stop for a DNS query. This server, or often servers for the sake of redundancy, is the highest authority for a given domain.

Not all DNS queries make it up to the authoritative nameserver, however, as there may be cached results closer to the initial request. Organizations also frequently use DNS internally. Some of the advantages of the system include:.

The developers of DNS always intended for the protocol to be extensible as technology progressed. Extensions to the original DNS standard have brought new features and functionality while still maintaining backward compatibility. New types of records, refined rules for the delivery of DNS packets, and enhanced security have all been added over the years. Many different DNS client and server implementations exist, but because they conform to a common standard they can all work together.

The first iterations of the Domain Name System DNS date to the early s, well before the emergence of modern cybersecurity threats. A variety of extensions and mitigations have been dreamt up in the ensuing years as new threats have emerged, but DNS is still often abused by attackers.

DNS is ubiquitous. Nearly every computer network in the world will see thousands to millions of DNS queries every single day. To enhance site performance it is important to reduce DNS lookups. The Root DNS server then responds with a pointer to forwards the DNS lookup request to the TLD nameserver that identifies the authoritative DNS server that is responsible for returning the corresponding site IP address of the website enabling the browser to access the desired website.

ThousandEyes is a network intelligence platform that delivers visibility into every network an organization relies on, enabling organizations to optimize and improve application delivery, end-user experience, and ongoing infrastructure investments. This is made possible through the ThousandEyes SaaS platform that allows customers to test application and network performance against assets owned by the organization, and assets owned by the organization's Service Providers SaaS, Outsourcers, etc.

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