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SOURCE VERIFIEDSource review Sep 8, 2026No hands-on test claimed2 sources

Docker container DNS resolution not working

Docker containers normally inherit or proxy DNS based on the network they use. Default-bridge containers receive resolver settings derived from the host, while custom networks use Docker’s embedded DNS. Loopback resolvers such as 127.0.0.1 on the host are a common mismatch because that address means the container itself inside its network namespace.

AuthorshipWritten and source-reviewed by Mihailo Ivanjac
Record created Sep 8, 2026Last source review Sep 8, 2026Source review only
SymptomDocker container dns not working.
Problem familyServers · Docker
Highest step riskAdvanced
Editorial statePublic launch · indexed
Affected scope
Docker Engine on LinuxBridge networksContainer DNSCustom Docker networks
Start here

Compare host, container and Docker network DNS paths

Compare DNS resolution on the host and inside the container, inspect the container’s /etc/resolv.conf and network type, and verify whether the host uses a loopback-only resolver. Configure Docker DNS only after proving the resolver path.

  1. Resolve the same hostname on the Docker host.
  2. Inspect /etc/resolv.conf inside the container.
  3. Inspect the Docker network and note whether it is default bridge or user-defined.
  4. Test a public name and any required internal name separately.

Why this branch first: Docker documents different resolver behavior for default bridge and user-defined networks.

Visual diagnosis

TroubleByte diagnostic path

01
Host

Test name resolution on the Docker host.

02
Container

Inspect container /etc/resolv.conf.

03
Network

Identify default or user-defined bridge behavior.

04
Configure

Set reachable DNS intentionally if inheritance is wrong.

Original TroubleByte diagnostic map. It summarizes the cited troubleshooting order; it is not a vendor screenshot.

Diagnosis

What this usually means

Container DNS behavior depends on network mode. Docker documents that default bridge containers get a copy of host resolver settings while custom networks use the embedded DNS server. A host loopback resolver cannot simply be used inside a container because 127.0.0.1 refers to the container namespace.

What the evidence establishes

What we verified from the source material

Docker documents that default bridge and user-defined networks handle DNS differently, and that host loopback resolvers can fail inside containers because loopback refers to the container namespace. Explicit DNS configuration should follow evidence about the required public or internal resolver path.

Before you change anything

Prerequisites and checks

Prepare first

  • Know whether the failed name is public, internal corporate DNS or another container name.
  • Avoid hard-coding public DNS if the container requires internal names.
  • Record any daemon DNS settings before changing them.

Checks that prevent the wrong fix

  • Test the same hostname on the Docker host.
  • Inspect /etc/resolv.conf inside the failing container.
  • Check whether the container uses the default bridge or a user-defined network.
Scope

Applies to

✓ Docker Engine on Linux✓ Bridge networks✓ Container DNS✓ Custom Docker networks
Troubleshooting path

Solutions, in order

01
SAFE · START HERE

Compare host, container and Docker network DNS paths

  1. Resolve the same hostname on the Docker host.
  2. Inspect /etc/resolv.conf inside the container.
  3. Inspect the Docker network and note whether it is default bridge or user-defined.
  4. Test a public name and any required internal name separately.

Why this can work: Docker documents different resolver behavior for default bridge and user-defined networks.

02
ADVANCED

Configure the intended resolver explicitly

  1. Identify DNS servers that are reachable from the Docker host/container network.
  2. Configure Docker/container DNS using supported options rather than editing generated resolv.conf manually.
  3. Recreate the container and verify resolution.

Why this can work: Docker supports explicit DNS configuration when inherited host settings are unsuitable, including loopback resolver cases.

Verification

How to know the fix actually worked

  1. The container resolves both required external and internal names after the change.
  2. Name resolution still works after the container is recreated.

Do not count a temporary disappearance of the symptom as a confirmed fix if the problem normally returns after a restart, reconnect or several minutes of use.

Stop conditions

When not to keep changing things

  • If only an internal/private DNS zone fails, do not replace it with public resolvers that cannot know that zone; configure the correct internal resolver instead.

Escalation: If Docker DNS remains inconsistent after resolver and network inspection, capture daemon/container network details and use Docker support or host-network diagnostics before rewriting application hosts files.

Evidence

Sources used for this record

Primary · checked Sep 8, 2026Docker — Networking overviewFirst-party documentation used as evidence for this troubleshooting record.Corroborating · checked Sep 8, 2026Docker — Troubleshooting the Docker daemonFirst-party documentation used as evidence for this troubleshooting record.
Who reviewed this

Mihailo Ivanjac

This record was written and source-reviewed by Mihailo Ivanjac. Source review means the cited documentation was checked against the troubleshooting order on this page; it does not imply a hands-on reproduction unless the page explicitly says so.

Author profile and editorial scope →
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Change log

Revision history

Show 1 recorded revision

2026-09-08 — Created for the v1.2 search-quality and content-scale pass from current first-party documentation; public indexing is controlled by the launch allowlist.