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TASK-86684: Adding dns_max_udp_queries_per_port to documentation #815

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Merged
dkoerichbird merged 1 commit into from
Jan 27, 2026
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TASK-86684: Adding dns_max_udp_queries_per_port to documentation #815

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1 change: 1 addition & 0 deletions content/momentum/4/config-options-summary.md
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Expand Up @@ -130,6 +130,7 @@ The `Version` column indicated the version(s) of Momentum that support the optio
| [dns_expire_interval](/momentum/4/config/ref-dns-expire-interval) – How often to check for domains with expired DNS information | sending | 10 | 4.0 and later | global |
| [dns_failures_to_purge](/momentum/4/config/ref-dns-failures-to-purge) – Configure the maximum number of DNS lookups | sending | 10 | 4.0 and later | domain, global |
| [dns_fallback_to_tcp](/momentum/4/config/ref-dns-fallback-to-tcp) – Whether or not to fail over to TCP in place of UDP | both | false | 4.0 and later | global |
| [dns_max_udp_queries_per_port](/momentum/4/config/ref-dns-max-udp-queries-per-port) - Limit the number of DNS queries sent using the same UDP source port | sending | 0 | 5.2 and later | global |
| [domain](/momentum/4/config/ref-domain) *(scope)* – Configure domain-specific options | sending |   | 4.0 and later | binding, binding_group, global |
| [domain_for_unqualified_recipient_addresses](/momentum/4/config/ref-domain-for-unqualified-recipient-addresses) – Configure a domain which will be used to resolve delivery for unqualified addresses | receiving |   | 4.0 and later | esmtp_listener, global, listen, pathway, pathway_group, peer |
| [domain_for_unqualified_sender_address](/momentum/4/config/ref-domain-for-unqualified-sender-address) – Configure a domain which will be used to substitute for unqualified sender addresses | receiving |   | 4.0 and later | esmtp_listener, global, listen, pathway, pathway_group, peer |
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1 change: 1 addition & 0 deletions content/momentum/4/config/index.md
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Expand Up @@ -66,6 +66,7 @@ description: "This chapter provides the definitions of the configuration options
| [dns_expire_interval](/momentum/4/config/ref-dns-expire-interval) | how often to check for domains with expired DNS information |
| [dns_failures_to_purge](/momentum/4/config/ref-dns-failures-to-purge) | configure the maximum number of DNS lookups |
| [dns_fallback_to_tcp](/momentum/4/config/ref-dns-fallback-to-tcp) | whether or not to fail over to TCP in place of UDP |
| [dns_max_udp_queries_per_port](/momentum/4/config/ref-dns-max-udp-queries-per-port) | limit the number of DNS queries sent using the same UDP source port |
| [domain_for_unqualified_recipient_addresses](/momentum/4/config/ref-domain-for-unqualified-recipient-addresses) | configure a domain which will be used to resolve delivery for unqualified addresses |
| [domain_for_unqualified_sender_address](/momentum/4/config/ref-domain-for-unqualified-sender-address) | configure a domain which will be used to substitute for unqualified sender addresses |
| [domain](/momentum/4/config/ref-domain) | configure domain specific options |
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26 changes: 26 additions & 0 deletions content/momentum/4/config/ref-dns-max-udp-queries-per-port.md
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---
lastUpdated: "01/31/2026"
title: "dns_max_udp_queries_per_port"
description: "dns max udp queries per port limit the number of DNS queries sent using the same UDP source port Momentum uses User Datagram Protocol UDP for DNS queries However the size of a UDP packet is limited and a DNS query can exceed it Set this option to..."
---

<a name="conf.ref.dns_max_udp_queries_per_port"></a>
## Name

dns_max_udp_queries_per_port — limit the number of DNS queries sent using the same UDP source port

## Synopsis

`dns_max_udp_queries_per_port = 10`

<a name="idp69432014"></a>
## Description

Momentum uses User Datagram Protocol (UDP) for DNS queries. Each internal channel to the DNS server(s) is assigned a dynamic (ephemeral) UDP source port number. All DNS queries sent over that channel use the same source port. When many queries originate from a single source port, security devices such as firewalls may interpret this pattern as malicious behavior (e.g., a DNS-based attack) and drop or block the queries. This setting limits how many DNS queries will be sent from each source port before Momentum allocates a new port number, helping to avoid triggering such security measures.

The default value is `0` (no limit). Most users do not need to change this value unless experiencing DNS-related firewall blocks.

<a name="idp69432015"></a>
## Scope

`dns_max_udp_queries_per_port` is valid in the global scope.