> Source: [sk106483](https://support.checkpoint.com/results/sk/sk106483)

# sk106483 - DNS packets are dropped by IPS protection "Non Compliant DNS" as attack "Bad domain format, empty domain"

| Property | Value |
|----------|-------|
| Solution ID | sk106483 |
| Date Created | 2015-06-16 |
| Last Modified | 2025-02-12 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R82.10, R81.10 (EOS) |

## Symptoms

- DNS packets are dropped by IPS protection "Non Compliant DNS" as attack "`Bad domain format, empty domain`".

## Cause

* IPS protection "Non-Compliant DNS" does not allow UDP DNS response packets that are larger than 512 bytes.
* If DNS UDP truncated response packets are allowed (*dns_allow_udp_truncated_msg=1*), then UDP DNS response packets with "TC" (Truncation Flag) may still be dropped if they are larger than 512 bytes.

## Solution

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