> For the complete documentation index, see [llms.txt](https://docs.console.zenlayer.com/welcome/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.console.zenlayer.com/welcome/elastic-compute/zdns-service/limit.md).

# Limit

ZDNS supports the following DNS record types: **A, AAAA, CNAME, MX, TXT, PTR, SRV**.

**Record Type Descriptions**

<table><thead><tr><th width="129.43603515625">Record Type</th><th width="173.219482421875">Description</th><th width="177.2684326171875">Host Record Format</th><th>Value Format Requirements</th></tr></thead><tbody><tr><td><strong>A Record</strong></td><td>Maps a domain name to an IPv4 address; supports wildcard entries.</td><td>Domain prefix</td><td>IPv4 address in dotted-decimal format (e.g., <code>192.168.1.2</code>). Multiple entries supported with optional weights.</td></tr><tr><td><strong>AAAA Record</strong></td><td>Maps a domain name to an IPv6 address; supports wildcard entries.</td><td>Domain prefix</td><td>IPv6 address (e.g., <code>ff03:0:0:0:0:0:0:c1</code>). Multiple entries supported with optional weights.</td></tr><tr><td><strong>CNAME Record</strong></td><td>Maps a domain name to another domain name, inheriting its resolution result.</td><td>Domain prefix</td><td>Domain format (e.g., <code>abc.example.com</code>).</td></tr><tr><td><strong>MX Record</strong></td><td>Specifies the mail server responsible for receiving emails.</td><td>Domain prefix</td><td>Domain format (e.g., <code>abc.example.com</code>).</td></tr><tr><td><strong>TXT Record</strong></td><td>Stores arbitrary text, commonly used for verification (e.g., SPF anti-spam checks).</td><td>Domain prefix</td><td>String format; allowed characters include letters, digits, and <code>*?-_~=:;.@+^/!”</code>.</td></tr><tr><td><strong>SRV Record</strong></td><td>Defines service records specifying which server provides a service.</td><td>Typically <code>_&#x3C;service>._&#x3C;protocol></code> (e.g., <code>_sip._tcp</code>)</td><td>Format: <code>[priority] [weight] [port] [target]</code>, each 0–65535, separated by spaces. Example: <code>0 5 5060 sipserver.example.com</code>.</td></tr><tr><td><strong>PTR Record</strong></td><td>Enables reverse DNS lookup (IP → domain name).</td><td>For IPv4, typically a number from 0–255</td><td>Domain format (e.g., <code>abc.example.com</code>). Example: For <code>192.168.0.1/24</code>, the zone name is <code>0.168.192.in-addr.arpa</code>, with record <code>5 -> abc.example.com</code>, meaning a query for <code>192.168.0.5</code> returns that domain.</td></tr></tbody></table>