---
title: DNS record management for external domains outside our control
description: "DNS SERVICE Guide ## Overview This manual outlines how to manage DNS records for **external domains not managed by us** (domains registered with another registrar) from our Client Area ([client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/)). The key point is to create a zone (domain…"
url: "https://bestnetllc.co.jp/en/docs/dns-record-management-for-external-domains-outside-our-control/"
updated: "2026-10-19"
category: DNS Service
---

# DNS record management for external domains outside our control

DNS SERVICE Guide

## Overview

This manual outlines how to manage DNS records for **external domains not managed by us** (domains registered with another registrar) from our Client Area ([client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/)).

The key point is to create a zone (domain for DNS management) in the [client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/), **migrate and create all necessary DNS records in advance**, and then **switch the nameservers (NS) to our DNS servers** at the external registrar.

   STEP 1 **Add Zone**

Create a zone for the target domain in DNS SERVICE in the Client Area.

   STEP 2 **Migrate Required Records**

Import current DNS settings or register them manually.

   STEP 3 **Switch NS**

Replace the nameservers with our DNS servers at the external registrar.

## Important (Read First: Preventing Incidents)

- **The moment you switch NS, the authoritative DNS switches to our DNS.** If the new zone does not have all the necessary records at the time of the switch, Web / email / various authentication services will be immediately affected.
- In particular, **email-related records (MX / SPF / DKIM / DMARC)**, **authentication TXT records** (Google / Microsoft / various SaaS / SSL auto-renewal, etc.), **CAA**, and **SRV** are often forgotten during migration.
- For domains with DNSSEC enabled, **updating or deleting DS records** may be necessary (see details below).

## Disclaimer and Support Information

- This manual outlines general operational examples. Required DNS records and migration procedures will vary depending on domain configuration and use of external services (email, various SaaS, SSL auto-renewal, etc.).
- We cannot be held responsible for indirect or consequential damages (lost opportunities, business interruptions, undelivered email, etc.) that result from following this procedure.
- **If you have any questions / difficulty determining impact scope / DNSSEC is enabled / migrating email as well**, please **open a [support ticket](https://bestnetllc.co.jp/en/encyclopedia/support-ticket-en/)** in our [client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/) for consultation before proceeding (we will provide guidance on items to verify based on your situation).

## Prerequisites (Preparation)

- Able to log into our [client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/)
- Your contract includes DNS SERVICE (DNS management service)
- You have authority to **change nameservers** at the domain registrar (e.g., Onamae.com / Cloudflare Registrar, etc.)
- Able to confirm current DNS settings (current DNS management panel, or zone file / record list)
- DNS record information you wish to add or modify (e.g., IP for A records, hostname for MX, TXT values, etc.)

## Pre-Switch Checklist (Recommended: Always Perform Before NS Switch)

- **Record current DNS record list** (A / AAAA / CNAME / MX / TXT / CAA / SRV / NS delegation, etc.)
- **Verify email-related TXT records**: SPF (`v=spf1`), DKIM (`selector._domainkey`), DMARC (`_dmarc`)
- **Verify authentication/automation TXT records**: `_acme-challenge`, Google / Microsoft / various SaaS verification TXT, etc.
- **Check for DNSSEC** (if enabled, refer to “DNSSEC Precautions”)
- **If switch date is determined**: Shorten TTL in advance if possible (e.g., 300-600 seconds)
  ※TTL reduction should be done first on the “current DNS side” and may take time to propagate.

## Procedure

### 1Open DNS SERVICE

Open **DNS SERVICE** from the left menu.

![Open DNS SERVICE](https://bestnetllc.co.jp/wp-content/uploads/2026/02/step-01-open-dns-service.png)
Open DNS SERVICE

### 2Add DNS Zone (External Domain)

2-1. Click “Add Domain”

In the DNS SERVICE management console, click **Add Domain**.

![Add Domain](https://bestnetllc.co.jp/wp-content/uploads/2026/02/step-02-add-domain-button.png)
Click “Add Domain”

2-2. Enter Domain Name and Submit

On the “Add New Zone” screen, enter the target domain.

- **Domain**: Enter the root domain **without www**, such as `example.com`
- **IP Address**: **Recommended to leave blank** (it is safer to explicitly add necessary records later)
  ※If you do enter an IP here for operational reasons, follow the screen specifications regarding whether an A record is automatically created or not.
- **Zone Content**: If existing DNS is present, it is safer to select **Import** (zone file / AXFR, etc.) if possible. If migrating manually, select “Add entries manually”.

After entering the information, click **Submit**.

![Add New Zone](https://bestnetllc.co.jp/wp-content/uploads/2026/02/step-03-add-zone-form.png)
Add New Zone

### 3(Recommended) Import / Manually Migrate Existing DNS Settings

**Before switching NS records**, migrate the records existing in the current DNS to our DNS service.
 This is the most critical step to prevent incidents.

- If possible, use “Import zone content” (zone file / AXFR, etc.).
- If import is not possible, manually create records while referencing the current DNS record list.

  **Commonly Missed Items During Migration**

- MX, SPF (TXT), DKIM (TXT), DMARC (TXT)
- Verification TXT records (Google / Microsoft / various SaaS)
- `_acme-challenge` (TXT) for SSL automatic renewal, etc.
- CAA, SRV, subdomain delegation (NS)

![Import Zone Content](https://bestnetllc.co.jp/wp-content/uploads/2026/02/step-08-import-zone.png)
Import Zone Content

### 4Add and Adjust DNS Records (Example: A Record)

4-1. Open the Target Domain (Zone)

From the domain list, click the domain name you want to edit to open the zone details.

![Open Zone Details](https://bestnetllc.co.jp/wp-content/uploads/2026/02/step-04-open-domain-zone.png)
Open Zone Details

4-2. Select Record Type and Click “Add”

In the “Add new record” section at the top of the zone details, select the record type you want to add (A / CNAME / MX / TXT, etc.), and click **Add**.

![Add New Record](https://bestnetllc.co.jp/wp-content/uploads/2026/02/step-05-add-record-button.png)
Add New Record

4-3. Enter Values and Submit

For an A record example, configure the following main settings:

- **Name**: For the root (@) equivalent, it is common to use the “default name” as is. For subdomains, specify `www`, etc. (enter according to screen specifications).
- **TTL**: The default is usually fine. You may adjust operationally, such as shortening it during the switchover period.
- **Content (IP Address)**: Enter the IP address you want to assign.

After entering the information, click **Submit**.

![Create A Record](https://bestnetllc.co.jp/wp-content/uploads/2026/02/step-06-create-a-record.png)
Create A Record

### 5Switch the Nameservers at Your External Registrar (Important)

To manage an external domain with our DNS service, you must **“replace”** the nameservers (NS) at your domain registrar (management company) with **the specified values of our DNS servers**.

1. In the zone details screen of the [client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/), check the NS (nameserver list).
2. In your external registrar’s management interface, **replace all** the domain’s nameservers with the above NS values.
   ※ Most registrars require “replacement,” not “addition.”

![Nameserver List](https://bestnetllc.co.jp/wp-content/uploads/2026/02/step-04-nameservers.png)
Nameserver List

  **Caution**

If you have not switched the nameservers, records added on our DNS service will not be referenced from external sources.

### 6Edit or Delete DNS Records

From the record list in the zone details, click **Edit** / **Delete** for the target row.

![Editing and Deleting DNS Records](https://bestnetllc.co.jp/wp-content/uploads/2026/02/step-07-edit-delete-record.png)
Editing and Deleting DNS Records

## DNSSEC Precautions (If Applicable)

- If DNSSEC is enabled for the target domain, **DS record mismatches** during NS switching may cause name resolution to fail.
- If DS record settings exist at the registrar, you must **delete / update the DS records according to the switching procedure**.
- The response varies depending on your operational policy (continue DNSSEC / temporarily disable it). If you are unsure, please **open a [support ticket](https://bestnetllc.co.jp/en/encyclopedia/support-ticket-en/)** from our [client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/) before proceeding.

## Verification (Functional Check)

- In the [client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/), verify that the added records appear in the zone details list
- After switching nameservers, verify that external name resolution works (authoritative NS is our NS)

External Verification Examples (Recommended)

  `dig NS example.com` `dig A example.com` `dig A www.example.com` `dig MX example.com` `dig +trace example.com`

**Note:** Nameserver changes and DNS propagation may take time. TTL, registrar reflection time, and cache status also affect this.

## Troubleshooting

   **External Name Resolution Fails**

- Verify that the NS at the registrar matches the NS values displayed in the zone details of the [client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/).
- Check if DNSSEC is enabled and DS records remain (see DNSSEC Precautions).

   **Incorrect Values Returned**

- Multiple records with the same name may exist (e.g., multiple A records, multiple TXT records).
- Check for CNAME conflicts with other records (CNAME and A / MX / TXT, etc. cannot coexist with the same name in principle).
- Use `dig` or similar tools for external verification to see which values are being returned.

   **Slow Propagation**

- The TTL may be long or cache may remain. Wait and recheck after some time.
- We recommend reducing the TTL during switching and restoring it to an appropriate value after completion.

   **Email Issues Only**

- Check that MX / SPF / DKIM / DMARC (TXT) records were not missed during migration.
- DKIM in particular involves many subdomain TXT records such as `selector._domainkey` and is easily overlooked.

## When You Need Help (Opening a [support ticket](https://bestnetllc.co.jp/en/encyclopedia/support-ticket-en/))

If you have any questions or encounter issues that persist after the switchover, please **open a [support ticket](https://bestnetllc.co.jp/en/encyclopedia/support-ticket-en/)** from our [client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/).

Including the following information will help us investigate more smoothly:

- Target domain name
- Registrar name (e.g., Onamae.com, etc.)
- Screenshot of the zone page in the [client portal](https://bestnetllc.co.jp/en/encyclopedia/client-portal-en/) (NS list and relevant record list)
- External verification results (e.g., output of `dig NS example.com` / `dig +trace example.com`)
- Description of the issue (e.g., website not loading, emails not being received, etc.) and the time it occurred