--- title: "Checking DNS settings" slug: "server-ts-dns-classic" tags: ["Classic"] updated: 2026-09-17T09:18:03Z published: 2026-09-17T09:18:03Z canonical: "guide.ncloud-docs.com/server-ts-dns-classic" --- > ## Documentation Index > Fetch the complete documentation index at: https://guide.ncloud-docs.com/llms.txt > Use this file to discover all available pages before exploring further. # Checking DNS settings Available in Classic If you do not use the DNS settings provided by NAVER Cloud Platform, normal communication with the servers provided for internal management may not be possible. If possible, do not set up DNS separately. If you set up DNS separately, you may encounter errors in the process of creating a server with a server image or setting the admin password. ## CentOS Inspect the DNS settings and file in the RedHat OS provided on NAVER Cloud Platform. Note Described for CentOS 7.2, CentOS 7.3, CentOS 7.8. 1. Check the DNS settings of NAVER Cloud Platform received from DHCP. The IPs of the DNS server provided in the Classic environment are `10.250.255.11` and `10.250.255.12`. ``` [root@centos78 ~]# grep domain-name /var/lib/dhclient/dhclient--eth0.lease option domain-name-servers 10.250.255.11,10.250.255.12; option domain-name "ncloud.com"; option domain-name-servers 10.250.255.11,10.250.255.12; option domain-name "ncloud.com"; ``` 2. Check the settings and content of the `/etc/resolv.conf` file. ``` [root@centos78 ~]# cat /etc/resolv.conf ; generated by /usr/sbin/dhclient-script search ncloud.com nameserver 10.250.255.11 nameserver 10.250.255.12 ``` - If the contents of the file differ from the following, normal communication with NAVER Cloud Platform DNS server may not be possible. However, after editing the file and rebooting the OS, it is initialized to NAVER Cloud Platform settings received from DHCP. 3. Run the `nslookup` command to check DNS query operation. ``` [root@centos78 ~]# nslookup repo.ncloud.com Server: 10.250.255.11 Address: 10.250.255.11#53 Non-authoritative answer: repo.ncloud.com canonical name = repo.ncloud.grm.ncloud.com. repo.ncloud.grm.ncloud.com canonical name = kr2-init.ncloud.grm.ncloud.com. Name: kr2-init.ncloud.grm.ncloud.com Address: 10.250.5.105 ``` - When the query works correctly, `10.250.5.105` is displayed. ## Ubuntu Ubuntu 18.04 provided by NAVER Cloud Platform uses systemd-resolved. Inspect the DNS settings and files on the Ubuntu OS. Note Described for Ubuntu 18.04. 1. Check the settings and content of the `/etc/resolv.conf` file. ``` root@ubuntu1804:~# ll /etc/resolv.conf lrwxrwxrwx 1 root root 39 Sep 28 2020 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf ``` - Check if the file's symbolic Link exists. 2. Check if the contents of the file are the same as the following: ``` root@ubuntu1804:~# cat /etc/resolv.conf # This file is managed by man:systemd-resolved(8). Do not edit. ... Omitted ... nameserver 127.0.0.53 options edns0 search ncloud.com ``` 3. Check the DNS settings of NAVER Cloud Platform received from DHCP. ``` root@ubuntu1804:~# cat /run/systemd/resolved.conf.d/isc-dhcp-v4-eth0.conf [Resolve] DNS=10.250.255.11 10.250.255.12 Domains= ncloud.com ``` 4. Check the configured DNS settings on the OS. The IPs of the DNS server provided in the Classic environment are `10.250.255.11` and `10.250.255.12`. ``` root@ubuntu1804:~# cat /run/systemd/resolve/resolv.conf ... Omitted ... nameserver 10.250.255.11 nameserver 10.250.255.12 search ncloud.com ``` - If it appears as follows, the DNS server settings are in an abnormal state. ``` root@ubuntu1804:~# tail -2 /run/systemd/resolve/resolv.conf # No DNS servers known. ``` - If applicable, handle it as follows: ``` root@ubuntu1804:~# cat /run/systemd/resolved.conf.d/isc-dhcp-v4-eth0.conf [Resolve] DNS=10.250.255.11 10.250.255.12 Domains= ncloud.com root@ubuntu1804:~# systemctl restart systemd-resolved root@ubuntu18:~# tail -3 /run/systemd/resolve/resolv.conf nameserver 10.250.255.11 nameserver 10.250.255.12 search ncloud.com ``` 5. Check if the `systemd-resolved` daemon is running and its status. - The `systemd-resolved` daemon must be `enabled` in the list of installed units so it can work properly after booting. ``` root@ubuntu1804:~# systemctl list-unit-files | grep systemd-resolved.service systemd-resolved.service enabled ``` - The `systemd-resolved` daemon must be `active` for normal operation. ``` root@ubuntu1804:~# systemctl status systemd-resolved.service ● systemd-resolved.service - Network Name Resolution Loaded: loaded (/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: enabled) Active: active (running) since Sun 2023-04-09 20:27:10 KST; 14h ago Docs: man:systemd-resolved.service(8) https://www.freedesktop.org/wiki/Software/systemd/resolved https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients Main PID: 687 (systemd-resolve) Status: "Processing requests..." Tasks: 1 (limit: 4622) CGroup: /system.slice/systemd-resolved.service └─687 /lib/systemd/systemd-resolved ``` - Check the connection status of the IP address `127.0.0.53`. It must be `LISTEN` through port 53 (nameservice port) by the `systemd-resolve` service. ``` root@ubuntu1804:~# netstat -anp | grep 127.0.0.53 tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN 687/systemd-resolve udp 0 0 127.0.0.53:53 0.0.0.0:* 687/systemd-resolve ``` 6. Check the DNS settings in the `systemd-resolve` service. - Use the following commands to verify the DNS server information that sends queries: ``` root@ubuntu1804:~# systemd-resolve --status Global DNS Servers: 10.250.255.11 10.250.255.12 ... Omitted ... ``` 7. Check the permissions of the `/etc/hosts` file. ``` root@ubuntu1804:~# ls -l /etc/hosts -rw-r--r-- 1 root root 189 Sep 28 2020 /etc/hosts ``` - Other User in the /etc/hosts file must have the read permission for the `systemd-resolved` daemon to operate properly. By default, the `/etc/hosts` file has permission set to 644. 8. Run the `nslookup` command to check DNS query operation. ``` root@ubuntu1804:~# nslookup repo.ncloud.com Server: 127.0.0.53 Address: 127.0.0.53#53 Non-authoritative answer: repo.ncloud.com canonical name = repo.ncloud.grm.ncloud.com. repo.ncloud.grm.ncloud.com canonical name = kr2-init.ncloud.grm.ncloud.com. Name: kr2-init.ncloud.grm.ncloud.com Address: 10.250.5.105 ``` - When the query works correctly, `10.250.5.105` is displayed. ## Changing the Fade-out DNS server If the confirmed DNS server settings are `125.209.192.12` or `125.209.192.13`, changing DNS server settings is required. Check if it should be changed and if so, proceed with changing the DNS server. ### Linux Caution The relevant guide target equipment only falls under some VMs of Classic. Do not run the action if it does not need to be changed. 1. Run the DNS server configuration change file and change the DNS server for the resolv.conf configuration. ``` [root@centos78 ~]# curl -sSL -k https://kr.object.ncloudstorage.com/dns-tools/resolv-change.sh | /bin/bash ``` - When you run the file, the DNS server automatically changes and a test is conducted to see if questioning is normally performed. - KR-1 Classic ![server-ts-dns-classic-01](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-dns-classic-01.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A49Z&se=2026-10-27T17%3A29%3A49Z&sr=c&sp=r&sig=ap2m5gG0EixPCYqXNPNX55%2Fluzmn9d5vPcH5QUN35gk%3D) - KR-2 Classic ![437E3170-9B18-4740-8905-05D9CBDF3182.jpg](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/437E3170-9B18-4740-8905-05D9CBDF3182.jpg?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A49Z&se=2026-10-27T17%3A29%3A49Z&sr=c&sp=r&sig=ap2m5gG0EixPCYqXNPNX55%2Fluzmn9d5vPcH5QUN35gk%3D) Caution DNS servers other than `125.209.192.12` and `125.209.192.13` are not changed by the task. Note If changing the DNS server fails, the operation result displays change failed as follows. If applicable, contact [customer support](https://www.ncloud.com/support/question/service): ``` [root@centos78 ~]# curl -sSL -k https://kr.object.ncloudstorage.com/dns-tools/resolv-change.sh | /bin/bash Task result: Change failed Failed to change resolv.conf settings. The required nameserver(s) not found. ``` ### Windows The following describes how to set DNS on Windows servers: 1. Connect to the Windows server. - For more information on how to connect to the server, see [access Windows server](/docs/en/server-access-vpc#Windows%EC%84%9C%EB%B2%84%EC%A0%91%EC%86%8D). 2. Click ![i-server_window_start](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/i-server_window_start.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A49Z&se=2026-10-27T17%3A29%3A49Z&sr=c&sp=r&sig=ap2m5gG0EixPCYqXNPNX55%2Fluzmn9d5vPcH5QUN35gk%3D), then click **Settings > Network & Internet > Change adapter options**, in order. - Alternatively, you can enter `ncpa.cpl` on the run command window. 3. On the list that appears, find the network you are using, right-click it and then click **Properties**. - In the Internet Protocol Version 4 (TCP/IPv4) Properties, edit Use the following DNS server addresses at the bottom to **10.250.255.11, 10.250.255.12**. Caution If you are operating your own DNS, such as Active Directory or DNS Server, check and change it as necessary. ## FAQs related to DNS ### Q. The following isc_socket_bind error occurs when querying DNS. What should I do? ``` [root@ncp-server ~]# nslookup repo.ncloud.com Server: 10.250.255.11 Address: 10.250.255.11#53 Non-authoritative answer: repo.ncloud.com canonical name = repo.ncloud.grm.ncloud.com. repo.ncloud.grm.ncloud.com canonical name = kr2-init.ncloud.grm.ncloud.com. Name: kr2-init.ncloud.grm.ncloud.com Address: 10.250.5.105 nslookup: isc_socket_bind: address in use ``` The issue occurs when the ip_local_port_range value is too small for the customer service network environment, or when there are too many socket ports currently in use. You can check the ip_local_port_range as follows. By default, the minimum port is 32768, and the maximum port is 60999: ``` [root@ncp-server ~]# sysctl net.ipv4.ip_local_port_range net.ipv4.ip_local_port_range = 32768 60999 ``` If the server can be rebooted, reboot in the OS. If it cannot be rebooted, check the number of currently used sockets and organize the unnecessary sockets or increase the ip_local_port_range value. DNS query in normal status is output as follows: ``` [root@ncp-server ~]# nslookup repo.ncloud.com Server: 10.250.255.11 Address: 10.250.255.11#53 Non-authoritative answer: repo.ncloud.com canonical name = repo.ncloud.grm.ncloud.com. repo.ncloud.grm.ncloud.com canonical name = kr1-init.ncloud.grm.ncloud.com. Name: kr1-init.ncloud.grm.ncloud.com Address: 10.101.86.18 ```