quarkusio/quarkus · warning · IllegalArgumentException

Unknown DNS record type:

Error message

Unknown DNS record type:

What it means

MongoDnsClient implements the driver's DnsClient SPI and resolves only SRV and TXT records, which are the only record types mongodb+srv:// discovery requires. Any other record type string passed to getResourceRecordData is rejected with this IllegalArgumentException.

Source

Thrown at extensions/mongodb-client/runtime/src/main/java/io/quarkus/mongodb/runtime/dns/MongoDnsClient.java:99

            try (Stream<String> lines = Files.lines(conf)) {
                nameServers = lines
                        .filter(line -> line.startsWith("nameserver"))
                        .map(line -> line.split(" ")[1])
                        .collect(Collectors.toList());
            } catch (IOException | ArrayIndexOutOfBoundsException e) {
                log.info("Unable to read the /etc/resolv.conf file", e);
            }
        }
        return nameServers;
    }

    @Override
    public List<String> getResourceRecordData(String name, String type) throws DnsException {
        log.debugf("Resolving DNS record for name: %s and type: %s", name, type);
        return switch (type) {
            case "SRV" -> resolveSrvRequest(name);
            case "TXT" -> resolveTxtRequest(name);
            default -> throw new IllegalArgumentException("Unknown DNS record type: " + type);
        };
    }

    /*
     * The format of SRV record is
     * priority weight port target.
     * e.g.
     * 0 5 5060 example.com.
     * The priority and weight are ignored, and we just concatenate the host (after removing the ending '.') and port with a
     * ':' in between, as expected by ServerAddress.
     * It's required that the srvHost has at least three parts (e.g. foo.bar.baz) and that all of the resolved hosts have a
     * parent
     * domain equal to the domain of the srvHost.
     */
    private List<String> resolveSrvRequest(final String srvHost) {
        List<String> hosts = new ArrayList<>();
        Duration timeout = mongoConfig.dnsLookupTimeout();

View on GitHub (pinned to e1c734241f)

Solutions

  1. Only request "SRV" or "TXT" record types from this client
  2. Check the type argument's exact casing — the switch is case-sensitive
  3. If you need A/AAAA resolution, use the standard DNS client (Vertx DnsClient) instead of the Mongo DnsClient SPI
  4. Ensure you're on matching versions of quarkus-mongodb-client and the driver so the SPI contract is honored

Example fix

// before
dnsClient.getResourceRecordData(host, "srv");
// after
dnsClient.getResourceRecordData(host, "SRV");
Defensive patterns

Strategy: type-guard

Validate before calling

// Only pass supported record types
if (!"SRV".equals(type) && !"TXT".equals(type)) {
    throw new IllegalArgumentException("MongoDnsClient supports only SRV/TXT, got: " + type);
}

Type guard

boolean isSupportedRecordType(String type) {
    return "SRV".equals(type) || "TXT".equals(type);
}

Try / catch

try {
    records = dnsClient.getResourceRecordData(name, type);
} catch (IllegalArgumentException e) {
    log.warn("Unsupported record type requested: " + type);
    records = List.of();
}

Prevention

When it happens

Trigger: The MongoDB driver's DNS resolution layer (or custom code using MongoDnsClient) requests a record type other than "SRV" or "TXT" from getResourceRecordData(name, type).

Common situations: Driver version behavior requesting A/AAAA records through this client; custom code calling the DnsClient SPI directly with the wrong type string; lowercase or padded type strings like "srv" instead of "SRV".

Related errors

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/2402680dc7fc7766. Report an issue: GitHub.