Ubuntu Manpage: dnsperf - test the performance of a DNS server

NAME

       dnsperf - test the performance of a DNS server

SYNOPSIS

       dnsperf [-a local_addr] [-b bufsize] [-B] [-c clients] [-d datafile] [-D] [-e]
       [-E code:secret] [-f family] [-h] [-l limit] [-m mode] [-n runs_through_file] [-p port]
       [-q num_queries] [-Q max_qps] [-s server_addr] [-S stats_interval] [-t timeout]
       [-T threads] [-u] [-v] [-W] [-x local_port] [-y [alg:]name:secret] [-O option=value]

DESCRIPTION

dnsperf is a DNS server performance testing tool. It is primarily intended for measuring
the performance of authoritative DNS servers, but it can also be used for measuring
caching server performance in a closed laboratory environment. For testing caching
servers resolving against the live Internet, the resperf program is preferred.

It is recommended that dnsperf and the name server under test be run on separate machines,
so that the CPU usage of dnsperf itself does not slow down the name server. The two
machines should be connected with a fast network, preferably a dedicated Gigabit Ethernet
segment. Testing through a router or firewall is not advisable.

Configuring the name server
If using dnsperf to test an authoritative server, the name server under test should be set
up to serve one or more zones similar in size and number to what the server is expected to
serve in production.

Also, be sure to turn off recursion in the server's configuration (in BIND 8/9, specify
"recursion no;" in the options block). In BIND 8, you should also specify "fetch-glue
no;"; otherwise the server may attempt to retrieve glue information from the Internet
during the test, slowing it down by an unpredictable factor.

Constructing a query input file
A dnsperf input file should contain a large and realistic set of queries, on the order of
ten thousand to a million. The input file contains one line per query, consisting of a
domain name and an RR type name separated by a space. The class of the query is
implicitly IN.

When measuring the performance serving non-terminal zones such as the root zone or TLDs,
note that such servers spend most of their time providing referral responses, not
authoritative answers. Therefore, a realistic input file might consist mostly of queries
for type A for names *below*, not at, the delegations present in the zone. For example,
when testing the performance of a server configured to be authoritative for the top-level
domain "fi.", which contains delegations for domains like "helsinki.fi" and "turku.fi",
the input file could contain lines like

www.turku.fi A
www.helsinki.fi A

where the "www" prefix ensures that the server will respond with a referral. Ideally, a
realistic proportion of queries for nonexistent domains should be mixed in with those for
existing ones, and the lines of the input file should be in a random order.

Constructing a dynamic update input file
To test dynamic update performance, dnsperf is run with the -u option, and the input file
is constructed of blocks of lines describing dynamic update messages. The first line in a
block contains the zone name:

example.com

Subsequent lines contain prerequisites, if there are any. Prerequisites can specify that
a name may or may not exist, an rrset may or may not exist, or an rrset exists and its
rdata matches all specified rdata for that name and type. The keywords "require" and
"prohibit" are followed by the appropriate information. All relative names are considered
to be relative to the zone name. The following lines show the 5 types of prerequisites.

require a
require a A
require a A 1.2.3.4
prohibit x
prohibit x A

Subsequent lines contain records to be added, records to be deleted, rrsets to be deleted,
or names to be deleted. The keywords "add" or "delete" are followed by the appropriate
information. All relative names are considered to be relative to the zone name. The
following lines show the 4 types of updates.

add x 3600 A 10.1.2.3
delete y A 10.1.2.3
delete z A
delete w

Each update message is terminated by a line containing the command:

send

Running the tests
When running dnsperf, a data file (the -d option) and server (the -s option) will normally
be specified. The output of dnsperf is mostly self-explanatory. Pay attention to the
number of dropped packets reported - when running the test over a local Ethernet
connection, it should be zero. If one or more packets has been dropped, there may be a
problem with the network connection. In that case, the results should be considered
suspect and the test repeated.

Using DNS-over-HTTPS
When using DNS-over-HTTPS you must set the -O doh-uri=... to something that works with the
server you're sending to. Also note that the value for maximum outstanding queries will
be used to control the maximum concurrent streams within the HTTP/2 connection.

OPTIONS

-a local_addr
Specifies the local address from which to send requests. The default is the
wildcard address.

-b bufsize
Sets the size of the socket's send and receive buffers, in kilobytes. If not
specified, the operating system's default is used.

-B
Instructs dnsperf to read datafile in TCP-stream binary format as specified by RFC
1035 section "4.2.2. TCP usage". Each packet is preceded by 2-byte preambule which
specifies length of the following DNS packet in network byte order, immediatelly
followed by raw bytes of the packet. First two bytes of any packet should contain
message ID and are overwritten by dnsperf on the fly. All other bytes are left
intact. Packets shorter than two bytes are sent intact. Packets in datafile can
contain arbitrary bytes and are not checked for validity. Malformed packets
probably will not be responded to by servers and will cause timeouts. This option
is mutually exclusive with -D, -e, -E, -u and -y.

These binary datafiles can be generated using arbitrary TCP listeners such as
netcat (nc) and sockat. TCP must be used so that the length is prepended.
Following example shows how to generate a datafile with two query and then using
it, you need two terminals.

(terminal 1) $ nc -l 127.0.0.1 5300 > dns.blob
(terminal 2) $ echo "example.com A" | dnsperf -s 127.0.0.1 -p 5300 -m tcp
(terminal 1) $ nc -l 127.0.0.1 5300 >> dns.blob
(terminal 2) $ echo "example.com AAAA" | dnsperf -s 127.0.0.1 -p 5300 -m tcp
(terminal 1) $ dnsperf -B -d dns.blob -s $IP

-c clients
Act as multiple clients. Requests are sent from multiple sockets. The default is
to act as 1 client.

-d datafile
Specifies the input data file. If not specified, dnsperf will read from standard
input.

-D
Sets the DO (DNSSEC OK) bit [RFC3225] in all packets sent. This also enables
EDNS0, which is required for DNSSEC. This option is mutually exclusive with -B.

-e
Enables EDNS0 [RFC2671], by adding an OPT record to all packets sent. This option
is mutually exclusive with -B.

-E code:value
Add an EDNS [RFC2671] option to all packets sent, using the specified numeric
option code and value expressed as a a hex-encoded string. This also enables
EDNS0. This option is mutually exclusive with -B.

-f family
Specifies the address family used for sending DNS packets. The possible values are
"inet", "inet6", or "any". If "any" (the default value) is specified, dnsperf will
use whichever address family is appropriate for the server it is sending packets
to.

-h
Print a usage statement and exit.

-l limit
Specifies a time limit for the run, in seconds. This may cause the input to be
read multiple times, or only some of the input to be read. The default behavior is
to read the input once, and have no specific time limit.

-n runs_through_file
Run through the input file at most this many times. If no time limit is set, the
file will be read exactly this number of times; if a time limit is set, the file
may be read fewer times.

-p port
Sets the port on which the DNS packets are sent. If not specified, the standard
DNS port (udp/tcp 53, DoT 853, DoH 443) is used.

-q num_queries
Sets the maximum number of outstanding requests. When this value is reached,
dnsperf will not send any more requests until either responses are received or
requests time out. The default value is 100.

-Q max_qps
Limits the number of requests per second. There is no default limit.

-m mode
Specifies the transport mode to use, "udp", "tcp", "dot" or "doh". Default is
"udp".

-s server_addr
Specifies the name or address of the server to which requests will be sent. The
default is the loopback address, 127.0.0.1.

-S stats_interval
If this parameter is specified, a count of the number of answers received per
second during the interval will be printed out every stats_interval seconds.

-t timeout
Specifies the request timeout value, in seconds. dnsperf will no longer wait for a
response to a particular request after this many seconds have elapsed. The default
is 5 seconds.

-T threads
Run multiple client threads. By default, dnsperf uses one thread for sending
requests and one thread for receiving responses. If this option is specified,
dnsperf will instead use N pairs of send/receive threads.

-u
Instructs dnsperf to send DNS dynamic update messages, rather than queries. The
format of the input file is different in this case; see the "Constructing a dynamic
update input file" section for more details. This option is mutually exclusive
with -B.

-v
Enables verbose mode. The DNS RCODE of each response will be reported to standard
output when the response is received, as will the latency. If a query times out,
it will be reported with the special string "T" instead of a normal DNS RCODE. If
a query is interrupted, it will be reported with the special string "I".
Additional information regarding network readiness and congestion will also be
reported.

-W
Log warnings and errors to standard output instead of standard error making it
easier for script, test and automation to capture all output.

-x local_port
Specifies the local port from which to send requests. The default is the wildcard
port (0).

If acting as multiple clients and the wildcard port is used, each client will use a
different random port. If a port is specified, the clients will use a range of
ports starting with the specified one.

-y [alg:]name:secret
Add a TSIG record [RFC2845] to all packets sent, using the specified TSIG key
algorithm, name and secret, where the algorithm defaults to hmac-md5 and the secret
is expressed as a base-64 encoded string. Available algorithms are: hmac-md5,
hmac-sha1, hmac-sha224, hmac-sha256, hmac-sha384 and hmac-sha512. This option is
mutually exclusive with -B.

-O option=value
Set an extended long option for various things to control different aspects of
testing or protocol modules, see EXTENDED OPTIONS for list of available options.

EXTENDED OPTIONS

doh-uri=URI
The URI to use for DNS-over-HTTPS, default value is "https://localhost/dns-query".

doh-method=HTTP_METHOD
The HTTP method to use when querying with DNS-over-HTTPS, default is GET.
Available methods are: GET, POST.

tls-sni=SERVER_NAME
The Server Name Indication (SNI) to use for TLS connections (such as DNS-over-TLS
or DNS-over-HTTPS), defaults to leaving out the SNI extension in the client hello.

suppress=MESSAGE[,MESSAGE,...]
Suppress various messages and warnings that may be shown excessively in some
situations, such as socket readiness when connecting to a slow service. Can
suppress multiple types by listing them as a comma separated list. Following type
are available.

timeouts: Suppress messages about queries being timed out
congestion: Suppress messages about network congestion
sendfailed: Suppress messages about failure to send packets or if only parts of the
packet were sent
sockready: Suppress messages about socket readiness
unexpected: Suppress messages about answers with an unexpected message ID
num-queries-per-conn=NUMBER
This will limit the number of queries sent over a connection before triggering a
re-connection. Once re-connected it will reset the counter and continue sending
queries until the limit is reached again, triggering another re-connection and so
on. Using this option will also enable counting number of responses received for
each connection and once the limit is reached for sending queries it will wait
until the same amount of responses has been received before re-connecting. Waiting
for responses may timeout and the timeout used for this is the same as specified by
-t. Note that this option is only useful for connection oriented protocols.

verbose-interval-stats
Change the statistics format of -S to that shown at end of run.

Please note: Min/max values for latency and connections are not available in
interval statistics. Number of answers received within stats_interval can
legitimately exceed number of queries sent, depending on answer latency, configured
timeout, and stats_interval.

Only available in dnsperf.

latency-histogram
Print detailed latency histograms for DNS answers and connections. Latency is
quantized into bins with roughly 3 % resolution, and latency range for individual
bins increases logarithmically. This is done to to limit amount of memory required
for histograms and also allows to visualize latency using logarithmic
percentile histograms with minimal postprocessing.

Only available in dnsperf and if compile time support was detected.

qps-threshold-wait=<microseconds>
When using -Q to rate limit queries sent, this option control the minimum time (in
microseconds) there should be between queries to use nanosleep() to wait until
sending the next query. Setting to zero (0) will disable any call to nanosleep()
between sending queries.

If the time between queries is lower then this, then no wait is performed in order
to have more precision on when to send the next query. This is because during high
QPS rate limiting it can take more time just calling the functions to wait for when
to send the next query then the actually time between queries.

If not set, the average call-time to nanosleep() will be measured during startup.