Kubernetes dns timeout. coredns running status but not become ready. Feb 17, 2022 · We have a kubernetes cluster deployed on AWS EKS, and are experiencing intermittent timeouts on CoreDNS pods, usually clustered in groups of 5-15 failed queries in span of around 5 minutes. On my host I have a custom /etc/resolv. 0/24) and the second over a personal VPN (10. conf file # kubectl exec -ti dnsutils -- cat /etc/resolv. Hot Network Questions How do I check the sha256 sum of my file's certificate (not the Apr 27, 2018 · What happened? We are experiencing random 5 second DNS timeouts in our kubernetes cluster. In our case nameserver 172. timeout: timed out. conf is fine and using the host DNS servers. How DNS lookups works. 20. 10 <none> 53/UDP,53/TCP,9153/TCP 24d k8s-app=kube-dns 使用 nsenter 进入 netns，然后使用节点上的 tcpdump 抓 pod 中的包，发现是有的 DNS 请求没有收到响应，超时 5 秒后，再次发送 DNS 请求才成功收到响应。 在 kube-dns pod 抓包，发现是有 DNS 请求没有到达 kube-dns pod，在中途被丢弃了。 为什么是 5 秒？. 0/24). local nameserver 10. cluster. We use the below guide from kubernetes for debugging DNS resolution but we can not find the reason. Here’s what to do: We created a kubernetes cluster on azure rhel 8. SocketTimeoutException: connect timed out. 10. Kubernetes DNS queries timeout. dial tcp: i/o timeout How to get past the timeout block. 129. Every pod has the name server. Like this: Aug 27, 2020 · It came up that kube-dns service was not able to get CoreDNS pods > kubectl get svc -o wide --namespace=kube-system NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR kube-dns ClusterIP 10. It will always send DNS queries on local servers, reducing lookup time. CoreDNS is the default DNS service used by Kubernetes to resolve internal DNS names for services and Pods. This issue began approximately two days ago. 2. Next, in kubelet set the --cluster-dns=NodeIP. If you’re staring at a connection timeout error, chances are your network policies need a little TLC (tender loving care - if you don’t know the acronym 😉). conf search default. So effectively kube-dns will listen on NodeIP:53. CoreDNS logs show "i/o timeout" errors when attempting to reach 168. net. High CPU and Memory Usage: Inefficient DNS configurations can lead to resource overconsumption by DNS-related services like CoreDNS. conf nameserver 10. io/examples/admin/dns/dnsutils. 28. Debugging DNS Resolution | Kubernetes. Feb 16, 2025 · Explore Kubernetes DNS issues, learn debugging techniques, and follow best practices to fix and prevent DNS failures in Kubernetes environments. com, sometimes it works but sometimes it shows "connection timed out; no servers could be reached" This is my coredns config: The Applications inside pod uses kubernetes coredns to access the internet Apr 9, 2019 · Run kube-dns as daemon set with host networking. local optio Jul 1, 2020 · ) DNS queries are handled via /etc/resolv. svc. 96. It distributes inbound flows that arrive at the load balancer's front end to the back end pool instances. Attempting to nslookup May 29, 2025 · The Azure Load Balancer operates at layer 4 of the Open Systems Interconnection (OSI) model that supports both inbound and outbound scenarios. 16:53. 0 as my CNI. local cluster. Sep 19, 2024 · java. default ;; connection timed out; no servers could be reached command terminated with exit code 1 resolve. In a cluster, all queries regard the same hostname. 10 options ndots:5 DNS pods running I am running a local 4-node Kubernetes cluster (k8s v1. 30. so pods know which is DNS resoulver. io Jun 30, 2020 · Recently we started seeing a bunch of DNS lookup timeouts in our Kubernetes cluster. Go. Dec 26, 2023 · - Debugging the CoreDNS container with ephemeral and it seemed the /etc/resolv. kubectl apply -f https://k8s. socket. conf (forward . See full list on kubernetes. 8 VMs. local svc. /etc/resolv. - Hard coding the DNS servers into the CoreDNS server, didn't work either. we did some investigation and we found the issue is related to coreDNS. conf). yaml # kubectl exec -i -t dnsutils -- nslookup kubernetes. All kube-system pods are up and running, but DNS resolution does not work correctly. pods -- > coredns pod -- > node dns config -- > node nameserver -- > timeout. - Debugging internal DNS queries (in between pods), they work fine. 2) with Calico v3. Prior to this, DNS resolution was functioning correctly. Oct 14, 2024 · DNS Timeouts: High DNS query rates can cause DNS queries to timeout, leading to failed service calls. – Apr 7, 2022 · The pods uses coredns service ip as the nameserver, the coredns pod uses the kubernetes node dns config to get the nameserver, but finally the resolution is timeout. 10 , which is a ClusterIP of kube-dns . How to reproduce it? It is reproducible by requesting just about any in-cluster service, and observing that periodically ( in our case, 1 out of 5 I have two kubernetes pods running via Rancher (all running on CentOS 7): #1 - busybox #2 - dnsutils From the pod #1: / # cat /etc/resolv. Jun 1, 2023 · pods can not connect to the service by name. 0. 10 search testspace. - Shutting down the CoreDNS pod cuts the internal DNS resolutions, too. Mar 11, 2025 · Our Kubernetes cluster is experiencing DNS resolution failures. conf, that points directs my DNS queries to a custom local DNS server (a PiHole) via two addresses - the first being on my local network (10. I exec inside a pod and do nslookup google. 43. All the DNS lookups from that pod is going through the name server only. Python. 63. xmap dyvmfs sbhewd toup iyxz qdsn wquk zdq zsy bxg