---
name: "dnsreplay"
section: "1"
platform: "linux"
package: "powerdns"
version: "5.1.5-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/dnsreplay"
---

# dnsreplay(1)

A PowerDNS nameserver debugging tool

## NAME

dnsreplay - A PowerDNS nameserver debugging tool

## SYNOPSIS

**dnsreplay** \[*OPTION*\]... *FILENAME* *ADDRESS* \[*PORT*\]

## DESCRIPTION

This program takes recorded questions and answers and replays them to the specified nameserver and reporting afterwards which percentage of answers matched, were better or worse.

**dnsreplay** compares the answers and some other metrics with the actual ones with those found in the dumpfile.

By default it will only replay queries with recursion-desired flag set.

## OPTIONS

- **FILENAME**

  is expected to be an PCAP file. The queries are send to the DNS server specified as *ADDRESS* and *PORT*.

- **ADDRESS**

  IPv4 or IPv6 address of the nameserver to replay *FILENAME* to.

- **PORT**

  if omitted, 53 will be used.

- **--help, -h**

  Show summary of options.

- **--ecs-mask** *\<VAL\>*

  When EDNS forwarding an IP address, mask out first octet with this value

- **--ecs-stamp** *\<FLAG\>*

  Add original IP address as EDNS Client Subnet Option when forwarding to reference server

- **--packet-limit** *\<NUM\>*

  Stop after replaying *NUM* packets. Default for *NUM* is 0, which means no limit.

- **--pcap-dns-port** *\<VAL\>*

  Look at packets from or to this port in the PCAP. Default is 53.

- **--quiet** *\<FLAG\>*

  If *FLAG* is set to 1, **dnsreplay** will not be very noisy with its output. This is the default.

- **--recursive** *\<FLAG\>*

  If *FLAG* is set to 1, **dnsreplay** will only replay queries with recursion desired flag set. This is the default.

- **--source-from-pcap** *\<FLAG\>*

  If *FLAG* is set to 1, **dnsreplay** will send the replayed queries from the source IP address and port present in the PCAP file. This requires IP\_TRANSPARENT support. Default is 0 which means replayed queries will be sent from a local address.

- **--source-ip** *\<VAL\>*

  Send the replayed queries from the source IP specified in *VAL*. Default is to send them from a local address.

- **--source-port** *\<VAL\>*

  Send the replayed queries from the source port specified in *VAL*. Default is to send from a random port selected by the kernel.

- **--speedup** *\<FACTOR\>*

  Replay queries with this speedup *FACTOR*. Default is 1.

- **--timeout-msec** *\<MSEC\>*

  Wait at least *MSEC* milliseconds for a reply. Default is 500.

## BUGS

dnsreplay has no certain handling for timeouts. It handles around at most 65536 outstanding answers.

## SEE ALSO

pcap(3PCAP), [tcpdump(8)](/tcpdump/8.md), [dnswasher(1)](/dnswasher/1.md)

## AUTHOR

PowerDNS.COM BV

## COPYRIGHT

PowerDNS.COM BV