# Glossary: DNS

Domain Name System, more commonly known as DNS, is a hierarchical decentralized naming system connected to the Internet or a private network. It translates domain names to the numerical IP addresses needed for locating and identifying services and devices on the network.

### TelcoBridges and DNS

Toolpack provides support for DNS and FQDN (fully qualified domain name) for SIP calls. FQDN is used in the signaling or in the media component of a call.

How the DNS is configured differs between each product line.

**ProSBC**

Based upon your system requirements, you can configure one or several DNS groups. Each group having one or several DNS servers sorted by priority.

#### TelcoBridges' DNS Implementation

TelcoBridges' DNS implementation works beside the SIP stack.

<br>

#### Supported DNS RFCs

TelcoBridges supports the following RFCs for DNS:

| Specification             | TMedia SIP stack support | Toolpack API Support | Media Gateway Application Support |
| ------------------------- | ------------------------ | -------------------- | --------------------------------- |
| RFC 1035 Domain Names     | Yes                      | Complete             | Complete                          |
| RFC 2782 DNS SRV Record   | Yes                      | Complete             | Complete                          |
| RFC 2915 NAPTR DNS Record | Yes                      | Complete             | Complete                          |

\[1] For more information, please contact [customer support](/troubleshooting-and-support/support-links/contacting-telcobridges-technical-support.md).

### Configuration

<table><thead><tr><th width="668">FreeSBC</th></tr></thead><tbody><tr><td><ul><li><a href="/pages/X0gsgjvVTNHNLQnSeeLc">v3.1: DNS configuration</a></li></ul></td></tr></tbody></table>

### References

* [Wikipedia article](https://en.wikipedia.org/wiki/Domain_Name_System)


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