# Caching Not working for NodeLocal DNSCache.

## Problem

* The NodeLocal DNSCache pods are failing to resolve the cached kubernetes service DNS queries.
* The DNS resolution for kubernetes services failing with `SERVFAIL` response.

## Environment

* Platform9 Managed Kubernetes – All Versions

## Cause

* The TTL of the records coming from CoreDNS is 30 Secs by default, hence any `.cluster.local` records would only be cached for 30s.

{% tabs %}
{% tab title="Javascript" %}

```javascript
kubernetes cluster.local in-addr.arpa ip6.arpa {
            pods insecure
            fallthrough in-addr.arpa ip6.arpa
            ttl 30
        }
```

{% endtab %}
{% endtabs %}

* Due to this any record cached in NodeLocal DNSCache pods would only be queryable for 30 Secs before it is expired from the cache.
* The DNS resolutions beyond 30 Secs will fail with a `SERVFAIL` response.

## Resolution

* The CoreDNS ConfigMap may be edited to set a higher TTL for any such domains; however, this can result in to a situation where these records will take longer to update in case their endpoint is updated.
* The ConfigMap/Corefile for the node-local-dns component would also need to be updated to allow a >30s maximum for any successful lookup record TTLs, e.g.

{% tabs %}
{% tab title="Javascript" %}

```javascript
cache {
            success 9984 60
            denial 9984 5
    }
```

{% endtab %}
{% endtabs %}

{% hint style="info" %}
**Info**

A similar issue was reported to upstream at

<https://github.com/kubernetes/dns/issues/415#issuecomment-712450686>
{% endhint %}


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