--- title: "Inspecting DNS configuration" slug: "server-ts-dns-vpc" tags: ["VPC "] updated: 2026-09-17T09:17:55Z published: 2026-09-17T09:17:55Z canonical: "guide.ncloud-docs.com/server-ts-dns-vpc" --- > ## 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. # Inspecting DNS configuration Available in VPC If you do not use the DNS settings provided on 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. ## NAVIX, CentOS, Rocky Linux Inspect the DNS settings and file in the RedHat OS provided on NAVER Cloud Platform. Note This guide covers NAVIX 9, CentOS 7, Rocky Linux 8, and Rocky Linux 9. 1. Check the DNS settings of NAVER Cloud Platform received from DHCP. The IPs of the DNS server provided in the VPC environment are `169.254.169.53` and `169.254.169.54`. ``` [root@centos78 ~]# grep domain-name /var/lib/dhclient/dhclient--eth0.lease option domain-name-servers 169.254.169.53,169.254.169.54; option domain-name-servers 169.254.169.53,169.254.169.54; ``` ``` [root@navix9 ~]# cat /var/lib/NetworkManager/dhclient-*.lease | grep domain-name-servers option domain-name-servers 169.254.169.53,169.254.169.54; ``` - CentOS 7, Rocky Linux 8 - NAVIX 9, Rocky Linux 9 2. Check the configuration and content of the /etc/resolv.conf file. 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. ``` [root@navix9 ~]# cat /etc/resolv.conf # Generated by NetworkManager nameserver 169.254.169.53 nameserver 169.254.169.54 ``` 3. Check the DNS query operation using the nslookup commands. When the query works correctly, `169.254.1.5` and `169.254.80.160` are displayed. ``` [root@navix9 ~]# nslookup repo.ncloud.com Server: 169.254.169.53 Address: 169.254.169.53#53 Non-authoritative answer: repo.ncloud.com canonical name = repo.ncloud.grm.ncloud.com. repo.ncloud.grm.ncloud.com canonical name = kr-vpc-init.ncloud.grm.ncloud.com. Name: kr-vpc-init.ncloud.grm.ncloud.com Address: 169.254.80.160 Name: kr-vpc-init.ncloud.grm.ncloud.com Address: 169.254.1.5 ``` When using a DNS other than the DNS provided on NAVER Cloud Platform, timeout may occur, or a completely different IP will be received. ``` [root@centos7 ~]# nslookup repo.ncloud.com 8.8.8.8 Server: 8.8.8.8 Address: 8.8.8.8#53 Non-authoritative answer: repo.ncloud.com canonical name = repo.ncloud.grm.ncloud.com. Name: repo.ncloud.grm.ncloud.com Address: 10.250.5.105 [root@navix9 ~]# nslookup repo.ncloud.com 8.8.8.8 ;; connection timed out; no servers could be reached ``` ## Ubuntu Inspect the DNS settings and files on the Ubuntu OS. Ubuntu 18.04 through 24.04 provided by NAVER Cloud Platform use systemd-resolved. Note Described for Ubuntu 18.04 through 24.04. 1. Check the configuration and content of the /etc/resolv.conf file. Check if the file's symbolic link exists. ``` root@ubuntu1804:~# ll /etc/resolv.conf lrwxrwxrwx 1 root root 29 Nov 13 2019 /etc/resolv.conf -> ../run/resolvconf/resolv.conf ``` ``` root@ubuntu2404:~# ll /etc/resolv.conf lrwxrwxrwx 1 root root 39 Aug 27 2024 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf ``` - Ubuntu 18.04 - Ubuntu 20.04 ~ 24.04 2. Check if the contents of the file are the same as the following. However, the `options edns0 trust-ad` option may be absent or different depending on the OS version. ``` root@ubuntu1804:~# cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) ... Omitted ... nameserver 127.0.0.53 ``` ``` root@ubuntu2004:~# cat /etc/resolv.conf # This file is managed by man:systemd-resolved(8). Do not edit. ... Omitted ... nameserver 127.0.0.53 options edns0 trust-ad ``` ``` root@ubuntu2404:~# cat /etc/resolv.conf # This is /run/systemd/resolve/stub-resolv.conf managed by man:systemd-resolved(8). ... Omitted ... nameserver 127.0.0.53 options edns0 trust-ad search . ``` - Ubuntu 18.04 - Ubuntu 20.04 - Ubuntu 22.04 ~ 24.04 3. Check the DNS settings of NAVER Cloud Platform received from DHCP. ``` root@ubuntu2004:~# cat /run/systemd/resolved.conf.d/isc-dhcp-v4-eth0.conf [Resolve] DNS=169.254.169.53 169.254.169.54 ``` ``` root@ubuntu2404:~# cat /run/systemd/netif/leases/* | grep DNS DNS=169.254.169.53 169.254.169.54 ``` - Ubuntu 18.04 ~ 20.04 - Ubuntu 22.04 ~ 24.04 4. Check the configured DNS settings on the OS. The IPs of the DNS server provided in the VPC environment are `169.254.169.53` and `169.254.169.54`. ``` root@ubuntu2404:~# cat /run/systemd/resolve/resolv.conf ... Omitted ... nameserver 169.254.169.53 nameserver 169.254.169.54 search . ``` If it appears as follows, the DNS server settings are in an abnormal state. ``` root@ubuntu2404:~# tail -2 /run/systemd/resolve/resolv.conf # No DNS servers known. ``` If applicable, handle it as follows: ``` root@ubuntu2404:~# cat /etc/systemd/resolved.conf.d/navercloud.conf [Resolve] FallbackDNS=169.254.169.53 ``` 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 for it to work properly after booting. ``` root@ubuntu2404:~# systemctl list-unit-files | grep systemd-resolved.service systemd-resolved.service enabled enabled ``` The `systemd-resolved` daemon must be `active` for it to work properly. ``` root@ubuntu2404:~# systemctl status systemd-resolved.service ● systemd-resolved.service - Network Name Resolution Loaded: loaded (/usr/lib/systemd/system/systemd-resolved.service; enabled; preset: enabled) Active: active (running) since Fri 2025-07-04 14:52:43 KST; 1h 27min ago Docs: man:systemd-resolved.service(8) man:org.freedesktop.resolve1(5) https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients Main PID: 409 (systemd-resolve) Status: "Processing requests..." Tasks: 1 (limit: 4611) Memory: 7.3M (peak: 7.9M) CPU: 474ms CGroup: /system.slice/systemd-resolved.service └─409 /usr/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@ubuntu2404:~# netstat -anp | grep 127.0.0.53 tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN 409/systemd-resolve udp 0 0 127.0.0.53:53 0.0.0.0:* 409/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: 169.254.169.53 169.254.169.54 ... Omitted ... ``` ``` root@ubuntu2004:~# systemd-resolve --status Global LLMNR setting: no MulticastDNS setting: no DNSOverTLS setting: no DNSSEC setting: no DNSSEC supported: no Current DNS Server: 169.254.169.53 DNS Servers: 169.254.169.53 169.254.169.54 ... Omitted ... ``` ``` root@ubuntu2404:~# resolvectl status Global Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported resolv.conf mode: stub Fallback DNS Servers: 169.254.169.53 Link 2 (eth0) Current Scopes: DNS Protocols: +DefaultRoute -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported Current DNS Server: 169.254.169.53 DNS Servers: 169.254.169.53 169.254.169.54 ``` - Ubuntu 18.04 - Ubuntu 20.04 - Ubuntu 22.04 ~ 24.04 7. Check the permissions of the /etc/hosts file. 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. ``` root@ubuntu2404:~# ls -l /etc/hosts -rw-r--r-- 1 root root 230 Jul 4 14:51 /etc/hosts ``` 8. Check the DNS query operation using the `nslookup` commands. When the query works correctly, `169.254.1.5` and `169.254.80.160` are displayed. ``` root@ubuntu2404:~# 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 = kr-vpc-init.ncloud.grm.ncloud.com. Name: kr-vpc-init.ncloud.grm.ncloud.com Address: 169.254.1.5 Name: kr-vpc-init.ncloud.grm.ncloud.com Address: 169.254.80.160 ``` When using a DNS other than the DNS provided on NAVER Cloud Platform, timeout may occur, or a completely different IP will be received. ``` root@ubuntu2004:~# nslookup repo.ncloud.com 8.8.8.8 Server: 8.8.8.8 Address: 8.8.8.8#53 Non-authoritative answer: repo.ncloud.com canonical name = repo.ncloud.grm.ncloud.com. Name: repo.ncloud.grm.ncloud.com Address: 10.250.5.105 root@ubuntu2404:~# nslookup repo.ncloud.com 8.8.8.8 ;; communications error to 8.8.8.8#53: timed out ;; communications error to 8.8.8.8#53: timed out ;; communications error to 8.8.8.8#53: timed out ;; no servers could be reached ``` ## DNS FAQs ### Q. The following isc_socket_bind error occurs when querying DNS. What should I do? ``` [root@ncp-server ~]# nslookup repo.ncloud.com Server: 169.254.169.53 Address: 169.254.169.53#53 Non-authoritative answer: repo.ncloud.com canonical name = repo.ncloud.grm.ncloud.com. repo.ncloud.grm.ncloud.com canonical name = kr-vpc-init.ncloud.grm.ncloud.com. Name: kr-vpc-init.ncloud.grm.ncloud.com Address: 169.254.80.160 Name: kr-vpc-init.ncloud.grm.ncloud.com Address: 169.254.1.5 nslookup: isc_socket_bind: address in use ``` The issue occurs when the ip_local_port_range value is too small for your 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: 169.254.169.53 Address: 169.254.169.53#53 Non-authoritative answer: repo.ncloud.com canonical name = repo.ncloud.grm.ncloud.com. repo.ncloud.grm.ncloud.com canonical name = kr-vpc-init.ncloud.grm.ncloud.com. Name: kr-vpc-init.ncloud.grm.ncloud.com Address: 169.254.80.160 Name: kr-vpc-init.ncloud.grm.ncloud.com Address: 169.254.1.5 ```