Glossary

An answer is the data associated with a DNS record that is the subject of a DNS query. Unlike traditional DNS software, NS1 treats answers as entities on their own, with all "potential" answers for a DNS record grouped under that record. This enables us to make complex decisions about which answers to return for a given record when we get a query for the record.

An answer group is a shared label allowing identifying metadata to be linked among a select number of possible answers. In NS1’s Filter Chain technology, answer groups are used to accomplish advanced routing goals. Refer to this article for more information.

A set of data corresponding to an individual answer (i.e., endpoint) within a DNS record. This data is referenced by the NS1 Filter Chain to determine the best answer to return for each DNS query in real-time. You can connect a monitor or other data source to a particular metadata field to configure automatic updates as network conditions change.

One of NS1's "traffic management" filters (part of the NS1 Filter Chain); This filter sorts or selects answers based on the lowest cost metadata value. Use this filter to always select the least expensive answer, or use it with the Pulsar Stabilize filter to always select the least expensive option as long as it is within the best performing option threshold you define. If you choose Select answers instead of sorting, only the answers with the lowest cost are selected.

A category of filters (part of the NS1 Filter Chain) that allow you to steer DNS traffic to specific record answers using an autonomous system number (ASN), IP prefix, or location.

One of NS1's "fencing" filters (part of the NS1 Filter Chain); This filter eliminates answers in which the country, subdivision, state, or province metadata does not match the requester’s location.

One of NS1's "fencing" filters (part of the NS1 Filter Chain); This filter eliminates answers from different geographical regions than the requester.

A category of filters (part of the NS1 Filter Chain) that are used to direct traffic based on geographic targets. Geotargeting filters help you create a prioritized list of answers that help clients reach their endpoints quickly without removing any option.

One of NS1's geographic filters (part of the NS1 Filter Chain); This filter sorts answers by the distance of the source IP address to the requested endpoint based on the country, subdivision, US state, or Canadian province.

One of NS1's geographic filters (part of the NS1 Filter Chain); This filter sorts answers by distance to the requester's IP address, using latitude and longitude coordinates.

One of NS1's geographic filters (part of the NS1 Filter Chain); This filter sorts answers based on the distance of the source IP address to the requested endpoint using the georegion metadata field and the GeoIP database.

One of NS1's "traffic management" filters (part of the NS1 Filter Chain); Ensures that the answer groups are always returned in the same order for an individual requester or subnet. Answers within the groups are returned in any order. Typically, this filter is used alongside the "Select First Group" filter to ensure the same requester is directed to the same group of answers.

A category of filters (part of the NS1 Filter Chain) that are used to eliminate answers that are currently down or experiencing higher traffic than the limits you define. There are two health check filters available for Filter Chain configuration: the Up and Shed Load filters.

Using a linked record avoids the timely and error-prone tasks of manually creating and maintaining identical configurations across multiple records. Linked records tell the NS1 authoritative server to use the full configuration from a target record that exists somewhere else on the NS1 platform. Note: The target record does not need to be in the same zone as the linked record. For example, a CDN using NS1 DNS services can instruct its customer (who is also using NS1) to use a linked record to point to the customer’s domain at the CDN, instead of a CNAME. This eliminates DNS round trips and (for A or AAAA records) allows direct resolution at the zone apex. A linked record can be any record type (A, MX, CNAME, etc.), but it must be the same type as a target or it will not resolve. Compared to a CNAME record, a linked record typically requires one less DNS lookup—often shortening the response time for the requesting resolver or user to receive the final answer. Linked records are specific to NS1, and their resolution is a completely internal process. During resolution, the full configuration from the target record (including advanced configuration options) is duplicated into the source record such that (other than the name of the record) they resolve identically. DNS recursors making the query will not be able to differentiate between a linked record and the “real” target to which it points. Linked records support all NS1 features and capabilities used by the target record—including real-time data feeds.

One of NS1's "fencing" filters (part of the NS1 Filter Chain); This filter eliminates answers whose ASN metadata value(s) do not match the autonomous system (AS) of the requester's IP address.

One of NS1's "fencing" filters (part of the NS1 Filter Chain); This filter eliminates answers in which the requester’s IP does not match the IP prefix list of the answer.

The unified delivery platform for NS1’s portfolio of application traffic automation and intelligence solutions. The cloud-based platform consolidates the deployment, configuration, and management of NS1 technologies for globally distributed, heterogenous application and network footprints.

NS1's Dedicated DNS solution enables fully redundant managed DNS services without the complexity and limitations of a multi-provider configuration. As an extension of our Managed DNS service, NS1 Dedicated DNS provides a physically and logically separated network with a single tenancy. It is delivered alongside NS1 Managed DNS on NS1 Connect, so you can configure and manage both networks from a unified cloud portal or API.

NS1's intelligent DNS query processing technology allows you to specify a set of rules within a DNS record to determine how each query is processed. Each Filter Chain configuration includes a sequence of filters that are applied in real-time to dynamically select the best answer for each DNS query.

NS1's global anycast managed DNS network which combines a resilient network, near-instant DNS propagation, and intelligent traffic steering to give enterprises modern controls over the user experience of internet-facing applications.

NS1's best-in-class China-specific DNS solution for global organizations enables traffic steering inside the territory. Managed DNS for China and name server acceleration to mitigate the performance impact of the “great firewall” for global or .cn domains, with a 2.5x improvement in DNS performance for users in China. NS1's Managed DNS for China shares a common management plane and API with NS1's global Managed DNS and Dedicated DNS networks.

One of NS1's "traffic management" filters (part of the NS1 Filter Chain); This filter orders all answers from highest (1) to lowest priority. Use this filter to always select a group of available answers or to implement failover in conjunction with filters like Up. If you select Select answers instead of sorting, only the answers with the highest priority are selected.

NS1's intelligent traffic steering solution — ideal for live streaming, multi-CDN, cloud, and edge delivery that uses real-user monitoring and highly customizable routing logic to optimize performance and cost at scale.

A Domain Name System (DNS) record is used to map a URL to an IP address. They are stored in DNS servers and contain critical information that helps navigate DNS traffic. For example, when a user searches for a URL is in a web browser, the URL is forwarded to the DNS servers and then directed to a specific web server based on the information outlined in the DNS record. A record is a basic unit of information in the DNS—identified by a domain name, a type (such as A, AAAA, MX, NS, etc.) indicating the type of information contained in the record, control information (such as TTL), and associated answer data (such as server IP addresses, mail hosts, etc.) depending on the record type. The most common record types are A (address), CNAME (canonical name), MX (mail exchange), NS (name server), PTR (pointer), SOA (start of authority), and TXT (text record).

Resolvers are often formed in two parts: a stub resolver which is often merely a library on a user’s computer, and a recursive resolver that will perform queries against nameservers before returning the result to the user. When searching for a domain, the resolver will start at the end of the domain and work its way back to the beginning.

One of NS1's "traffic management" filters (part of the NS1 Filter Chain); This filter selects answers that are only in the same region as the first answer. Use this filter with other filters like Group Sticky Shuffle to group answers by region.

One of NS1's "traffic management" filters (part of the NS1 Filter Chain); This filter eliminates all but the first N answers from the list. Use this filter with filters like Shuffle or Weighted Shuffle to implement a round-robin or weighted round-robin approach to the number of responses that you return.

One of NS1's "health check" filters (part of the NS1 Filter Chain); This filter eliminates answers in which the load is higher than the defined limits, resulting in slow or stopped traffic to high-traffic or overloaded endpoints. You must select a metric type — load average, average connections, or active requests — and then define low and high watermark values for that metric. This filter is used often to configure automatic load shedding where users create a data feed to automatically update load metrics within the answer metadata.

One of NS1's "traffic management" filters (part of the NS1 Filter Chain); This filter randomly sorts answers. Use this filter with other filters like Select First N to return a subset of the available answers at random.

A category of filters (part of the NS1 Filter Chain); Sticky filters aim to distribute traffic across multiple answers while ensuring DNS queries from the same source IP address are handled consistently over time.

One of NS1's "traffic management" filters (part of the NS1 Filter Chain); This filter performs a shuffle to ensure that answers are always returned in the same order for an individual requester or subnet.

A category of filters (part of the NS1 Filter Chain); Traffic management filters help you shuffle, weight, prioritize, sort, and select answers based on the metadata and options that you define.

One of NS1's "health check" filters (part of the NS1 Filter Chain); This filter eliminates answers in which the "up" metadata value is not true or 1, or if it is not set.

One of NS1's "traffic management" filters (part of the NS1 Filter Chain); This filter reorders answers randomly based on the weight metadata value until all answers are randomly reordered. Answers with a higher weight value will be returned first more often. You can use this filter with the Select First N filter to return one or more answers with probability proportional to their weights.

One of NS1's "traffic management" filters (part of the NS1 Filter Chain); This filter combines Sticky Shuffle and Weighted Shuffle to randomly shuffle answers based on the weight metadata field, consistently across the same requester IP address. Changing a set of answers or their weight value results in a reshuffling. If you select "Apply stickiness by subnet (not by individual IP)", requests in the same IPv4 or IPv6 subnet receive the same output. Select this option to ensure that users balanced across multiple recursors get the same answer.

A DNS zone is simply a domain name (like yourdomain.com) and all subdomains associated with it (like www.yourdomain.com). In the DNS, you delegate "authority" for a zone to a DNS provider like NS1, which then serves as the database of records when lookups are done for information in your zone. You can also think of a zone as a collection of related DNS records.