<div dir="ltr"><div>Hey bind-users,</div><div><br></div><div>I have a few questions concerning qps-scale.</div><div><br></div><div>
<div>Referencing: <a href="https://owa-fb-cafrfd1msg.it.att.com/owa/redir.aspx?C=sSqMGF1uxBG_j8W0xquXski4L4SoQskiWWmybazKp7lMkYbtVXbWCA..&URL=https%3a%2f%2furldefense.proofpoint.com%2fv2%2furl%3fu%3dhttp-3A__www.zytrax.com_books_dns_ch7_hkpng.html-23rate-2Dlimit%26d%3dDwMFAw%26c%3dLFYZ-o9_HUMeMTSQicvjIg%26r%3dZJSnpAJR1u4VhPcjyvD0AA%26m%3dP2MSVkggLXM0ET_O0pOqhmjna546AOxekpqML0mUinA%26s%3ddMYw3YORsrcfXyB1nj1B2ZkwF7OsULwy11uwS8N31y4%26e%3d" target="_blank" rel="noopener noreferrer">
http://www.zytrax.com/books/dns/ch7/hkpng.html#rate-limit</a> and</div>
<div><a href="https://owa-fb-cafrfd1msg.it.att.com/owa/redir.aspx?C=H_KumoXkqxMJqV_AGREj5-rYPsMhQ-aD2rD3X4pZ8vtMkYbtVXbWCA..&URL=https%3a%2f%2furldefense.proofpoint.com%2fv2%2furl%3fu%3dhttps-3A__ftp.isc.org_isc_bind9_9.10.8-2DP1_doc_arm_Bv9ARM.pdf%26d%3dDwMFAw%26c%3dLFYZ-o9_HUMeMTSQicvjIg%26r%3dZJSnpAJR1u4VhPcjyvD0AA%26m%3dP2MSVkggLXM0ET_O0pOqhmjna546AOxekpqML0mUinA%26s%3d6spMSKoM_6XBqle0aw8wgetJH2j56gc_8rZRRaCWURM%26e%3d" target="_blank" rel="noopener noreferrer">https://ftp.isc.org/isc/bind9/9.10.8-P1/doc/arm/Bv9ARM.pdf</a>
 Page 119</div>
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<div>Definition:</div>
<div>Range allowed is 1 to very big number (actually 32 bit unsigned 
value, which is still a very big number). Default is not to apply 
qps-scaling. The rate limiting function calculates the approximate query
 per second load on the DNS from all sources (including
 TCP queries). The <b>qps-scale</b>, if defined, is then applied which may result in a reduction of the user supplied limits, such as
<b>responses-per-second</b> during high-load situations. Thus, assume the user defined
<b>responses-per-second 10;</b> and a <b>qps-scale 200;</b> then if the 
DNS server is receiving queries (from all sources, including TCP) at a 
rate of 500 per second the following algorithm is applied (qps-scale/DNS
 query arrival rate) * responses-per-second
 = effective rate-limit, substituting actual values gives (200/500) * 10
 = 4, meaning that in the defined load conditions the 5th and subsequent
 identical response in any 1 second to any specific client will be 
dropped (or trigger any defined
<a href="https://owa-fb-cafrfd1msg.it.att.com/owa/redir.aspx?C=d-0CB5Uei3m4HURi5fkwNHGwKVbOxcxTDoCD7AH_7fVMkYbtVXbWCA..&URL=https%3a%2f%2furldefense.proofpoint.com%2fv2%2furl%3fu%3dhttp-3A__www.zytrax.com_books_dns_ch7_hkpng.html-23slip%26d%3dDwMFAw%26c%3dLFYZ-o9_HUMeMTSQicvjIg%26r%3dZJSnpAJR1u4VhPcjyvD0AA%26m%3dP2MSVkggLXM0ET_O0pOqhmjna546AOxekpqML0mUinA%26s%3daZbaZPsBlPP26rWZluczEsYfVy7P8rI9riO6jfbLoc4%26e%3d" class="gmail-t-db" target="_blank" rel="noopener noreferrer">
slip</a> parameter action). The <b>qps-scale</b> value, if used, should thus be set to the maximum desired DNS transaction (query response) rate for the server.</div>
<div><a href="https://owa-fb-cafrfd1msg.it.att.com/owa/redir.aspx?C=sSqMGF1uxBG_j8W0xquXski4L4SoQskiWWmybazKp7lMkYbtVXbWCA..&URL=https%3a%2f%2furldefense.proofpoint.com%2fv2%2furl%3fu%3dhttp-3A__www.zytrax.com_books_dns_ch7_hkpng.html-23rate-2Dlimit%26d%3dDwMFAw%26c%3dLFYZ-o9_HUMeMTSQicvjIg%26r%3dZJSnpAJR1u4VhPcjyvD0AA%26m%3dP2MSVkggLXM0ET_O0pOqhmjna546AOxekpqML0mUinA%26s%3ddMYw3YORsrcfXyB1nj1B2ZkwF7OsULwy11uwS8N31y4%26e%3d" target="_blank" rel="noopener noreferrer">http://www.zytrax.com/books/dns/ch7/hkpng.html#rate-limit</a></div>
<div><br>
</div>
<div>My questions:</div>
<div>With my understanding reading the definition above, the "DNS query 
arrival rate" is the current number of queries per second being sent to 
the DNS server which changes dynamically
<b>NOT</b> the capacity of queries per second the DNS server is able to handle.</div>
<div>Is my understanding true?</div>
<div><br>
</div>
<div>How is the "DNS query arrival rate" calculated by the DNS server? How often is the "DNS query arrival rate" calculated? My thinking is every second.<br></div>
<div><br>
</div>
<div>If the qps-scale is defined, not 0, will the qps-scale formula <b>always </b>
be used?</div>
<div>For example: qps-scale 500; responses-per-second 50; "DNS query arrival rate" 200</div>
<div>(500 / 200) * 50 = 125 effective responses-per-second</div>
<div>or</div>
<div>is the qps-scale formula only used when the "DNS query arrival rate" is approximate or exceeds the qps-scale value?</div>
<div><br>
</div>
<div>Thanks</div>
<div>Brent D</div>

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