# mDNS: Response from 192.168.1.50:5353 does not match query for _http._tcp.local, ignoring

- **ID:** `networking/mdns-response-mismatch`
- **Domain:** networking
- **Category:** protocol_error
- **Verification:** ai_generated
- **Fix Rate:** 75%

## Root Cause

A multicast DNS responder sent a response that does not correspond to the query's question section, often due to a misconfigured service advertisement or a buggy mDNS implementation that replies with unrelated records, causing the client to discard the response.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| Avahi 0.8 | active | — | — |
| systemd-resolved 252 | active | — | — |
| Bonjour (macOS Ventura) | active | — | — |

## Workarounds

1. **tcpdump -i eth0 port 5353 -X | grep -A5 'mDNS'** (80% success)
   ```
   tcpdump -i eth0 port 5353 -X | grep -A5 'mDNS'
   ```
2. **iptables -A INPUT -s 192.168.1.50 -p udp --dport 5353 -j DROP** (70% success)
   ```
   iptables -A INPUT -s 192.168.1.50 -p udp --dport 5353 -j DROP
   ```

## Dead Ends

- **Clearing the local mDNS cache using systemd-resolved or Avahi commands.** — The cache is not the issue; the problem is the responder sending mismatched responses. Flushing cache only removes local entries, not the faulty responder behavior. (90% fail)
- **Adjusting TTL on mDNS records to reduce query frequency.** — Does not address the mismatch in response; the responder will still send incorrect replies regardless of TTL. (85% fail)