{"id":1344,"date":"2021-05-10T12:03:16","date_gmt":"2021-05-10T09:03:16","guid":{"rendered":"https:\/\/www.scalahosting.com\/kb\/?p=1344"},"modified":"2022-06-08T15:11:44","modified_gmt":"2022-06-08T12:11:44","slug":"what-is-an-soa-record","status":"publish","type":"post","link":"https:\/\/www.scalahosting.com\/kb\/what-is-an-soa-record\/","title":{"rendered":"What is an SOA Record?"},"content":{"rendered":"

An SOA record means <\/span>Start of Authority<\/b>. The record holds <\/span>specific authoritative information<\/b> about the global parameters of a DNS zone.\u00a0<\/span><\/p>\n

This includes information on the <\/span>primary name server<\/b><\/a>, the domain\u2019s serial number, the domain administrator\u2019s email, and several timers for refreshing the zone.<\/span><\/p>\n

Therefore, an<\/span> SOA resource record<\/b> shows what <\/span>DNS server hosts<\/b> the most accurate information for a specified domain. It also changes anytime the DNS settings change.<\/span><\/p>\n

How do SOA Records Work?<\/b><\/h2>\n

The SOA records are the basis of the <\/span>DNS zone files.<\/b> The DNS structure is a <\/span>decentralized, hierarchical system<\/b>, with the SOA resource records at the top and the slave or secondary servers at the bottom.\u00a0<\/span><\/p>\n

While there are many name servers, they do not supply information to random servers but name servers in an allocated zone.<\/span><\/p>\n

For this reason, <\/span>DNS servers handle zone files<\/b> which are text files that contain a zone\u2019s <\/span>DNS records<\/b><\/a>.<\/b> Each zone file must have an SOA record to determine the various authoritative servers for that domain.\u00a0<\/span><\/p>\n

This process makes it the Start of Authority by providing information on whether or not a server is authoritative enough to handle a query.<\/span><\/p>\n

The SOA\u2019s mode of operation makes it <\/span>essential to the DNS system<\/b><\/a>. Rather than one server bearing the brunt of all queries, they\u2019re spread among many servers. A zone transfer must be done regularly <\/span>to keep the zone files updated<\/b> on all servers.<\/span><\/p>\n

To do this, the servers at the lowest hierarchy sync their data with the <\/span>primary servers at the top of the DNS system.<\/b> The SOA record governs how the zone transition takes place.<\/span><\/p>\n

The SOA Record Structure<\/b><\/h2>\n

The SOA record has several fields containing relevant information that helps it function.\u00a0<\/span><\/p>\n

We’ll take a look at them shortly.<\/span><\/p>\n

MName<\/b><\/h3>\n

This is the domain name of the <\/span>primary (master) name server<\/b> for a specific zone.<\/span><\/p>\n

RName<\/b><\/h3>\n

This field contains the <\/span>email address of the domain administrator<\/b>. When formatting the email address, you must exclude the <\/span>@ symbol<\/b> and replace it with a period<\/span> (.)<\/b>. The period separates the username from the domain.\u00a0<\/span><\/p>\n

In cases where you have a period before the <\/span>@ symbol <\/b>in the main address, you must replace it with a backslash <\/span>(\\).<\/b><\/p>\n

When you\u2019ve effected the changes, this email \u2014 <\/span>sample@scalahosting.com<\/b> becomes this \u2014 <\/span>sample.scalahosting.com. <\/b>And, <\/span>blog.sample@scalahosting.com<\/b> becomes, <\/span>blog\\.sample.scalahosting.com.<\/b><\/p>\n

In essence, the email address is written in <\/span>DNS format<\/b>, not email format.<\/span><\/p>\n

Serial Number<\/b><\/h3>\n

This is the serial number to a<\/span> specific zone<\/b>. It is a timestamp that changes each time you update your zone files.<\/span><\/p>\n

When a <\/span>secondary name server<\/b> observes an increase in the number, it initiates zone transfers using that value to update its copy of the zone.<\/span><\/p>\n

Anytime you change the zone files, you must <\/span>overwrite the serial number<\/b> using any of the following methods.<\/span><\/p>\n

Increment it by one integer – <\/b>If your current SOA serial number is <\/span>105<\/b>, change it<\/span> to <\/span>106<\/b> when you make a change to the file data.\u00a0<\/span><\/p>\n

If you don\u2019t alter the values, the domain\u2019s secondary name servers won\u2019t <\/span>update their copy of the database<\/b>, causing both primary <\/span>(master)<\/span><\/i> and secondary <\/span>(slave)<\/span><\/i> servers to be out of sync.<\/span><\/p>\n

Use the date format – <\/b>The acceptable date format is <\/span>YYYYMMDDVV<\/b>.\u00a0<\/span><\/p>\n

Where each of them means :\u00a0<\/b><\/p>\n