consideration on dns service level
DESCRIPTION
Consideration on DNS Service Level. Shinta Sato [email protected] Japan Registry Service Co., Ltd. Oct. 29, 2002. What is a service level of DNS operation? How to measure a service level? How to maintain a service level? How to cooperate with users to maintain a service level?. Background. - PowerPoint PPT PresentationTRANSCRIPT
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Consideration on DNS Service Level
Shinta [email protected]
Japan Registry Service Co., Ltd.Oct. 29, 2002
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
• What is a service level of DNS operation?• How to measure a service level?• How to maintain a service level?• How to cooperate with users to maintain a service
level?
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Background
• DNS service level is a common interest among (ccTLD) DNS operators– DNS is one of the most important services that all
ccTLDs provide
– name servers seems to be easily set up and maintained, but reality is…
– Are they really working stable enough?
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
• From observation in query rate monitoring– Remarkable increase of queries was found
– Caused by continuous queries from a few servers
In the Case of JP DNS Operation
Oct. 2002
(ave. 700qps)
Dec. 2001
(ave. 350qps)
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Service Level
• Service Level can be a guideline to know how well the DNS is operated
• Benefits for the service providers– A guiding principle of management and control of the
services
– Stability of service quality
– Reliance of their customers
• Benefits for the customers– Guarantee of stable service quality
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
What is Service Level of DNS
• Need to define SLO (Service Level Objectives)– Availability
• Name servers are online and answering the queries
– Performance• Name servers give an answer to the clients in a response time
short enough
– Zone file• How frequently the zone files are created
• How long it takes to make them appear in name servers
– and so on
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Approaches to Service Level:gTLD Case
• SLA of DNS service on .com / .info / .pro agreement– SLA is made between registry and registrar
– SLA on other services than DNS also made (depends on gTLDs)
• WHOIS, RRP and so on
– Service Level Objectives (vary among gTLDs)• Availability, Performance and so on
– Standard of measurement (vary among gTLDs)
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Approaches to the Service Level: .jp Case
• DNS service level aspects– Service availability
– Performance
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
How to Measure a Service Level?
• Availability measurement• Performance measurement
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Availability Measurement Done by JPRS
• Query to all name servers to see if it is working– Availability checks for the name server hosts can be
done by “ping” command
– Availability checks for the DNS service can be done by “dig” command
• Check continuously and keep them recorded– Check every 5 minutes
– Various monitoring tools available
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Performance measurement on .jp
• CNNP (Cross Network Name server Performance) Test:– measuring the response time of the TLD servers from specified
points of the Internet• Development of measuring tools
• Development of data correction tools
• Measuring procedure:– Contact to an access point (dial-up or other methods)– DNS queries to the target name servers– Apply some data correction method
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
How to Maintain a Service Level?
• Understanding the current status• Estimation• Action
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Measurement Done by JPRS• Purpose: To collect the information of the current DNS service
level on .jp and some TLDs (gTLDs and ccTLDs)• Target: Primary and secondary DNS servers of those TLDs
– the servers described in root zone file
• Measuring point:– Access points covering 10 countries
• jp, kr, cn, tw, hk, au, us, it, uk, de • Roaming access provided by GRIC / UUNET / Nifty
• Procedure:– At each measuring point, response times for all name servers of a target
TLD are measured– Make some data corrections
• Overhead time by dial-up access, …
– Find the fastest answer
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
.jp DNS Performance
• .jp DNS servers
• Response time
050
100150200250300350
jp
kr
cn
tw
hk
au
us
it
uk
de
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Observation of .jp DNS
• From the figure– Response time of the queries is long from European
countries
– AP region has shorter response time
• Where to place name servers– Distribution of JP DNS query should be considered
together with response time
– Distribution by• Geographic regions?
• Network regions? (for example AS)
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Results of other TLDs
• gTLDs (com / org / net) • a ccTLD in Europe
050
100150200250300350
jp
kr
cn
tw
hk
au
us
it
uk
de
050
100150200250300350
jp
kr
cn
tw
hk
au
us
it
uk
de
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Future Works
• Determine DNS service levels– Index? (availability & performance?)– Criteria?
• Build up a management process for service level maintenance
• Infrastructure planning based on service policies– Number of DNS servers– Machine power of DNS servers– Where DNS servers should be placed– Level of enforcement on DNS server operators
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Standard for Evaluations
• Need to define requirements of Service Level– Goals
• Response time 100ms?
• 99.99% for each name servers availability?
– Permissible level• Response time 300ms?
• 99.99% for total availability of authoritative name servers?
– Minimum level• Response time 500ms?
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
How to Cooperate with Users to Maintain a Service Level
• DNSQC-TF (JPNIC/JPRS/WIDE)– DNS Quality Checking project– Check for the lame delegations and
misconfigured name servers under JP domains
• Performance investigations (WIDE Project)– Target: Root servers and ccTLD servers
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Proposal from JPRS
• Cooperation among ccTLDs– Determination of measuring method and tools
– Widely distributed / long range measuring activities
– Collocation of name servers with each other
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Joint Effort of ccTLDs: why needed?
• The internet is a huge and widely distributed network and is a set of many autonomous systems.
• Thus, measuring from few specific points will not be enough for estimation of DNS service level.
• More measuring points desirable.
• Joint effort of ccTLDs can be a good solution for this• We can have so many measuring points covering various
countries / AS’s around the world
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Japan Registry ServiceJapan Registry Service
Copyright © 2002 Japan Registry Service Co., Ltd.
Joint Effort of ccTLDs: What and How
• Set up a working group• Issues
– On performance measuring• Development of the tools• Standardize the method (CNNP test?)• Share the measuring points on each countries
– Information exchange– Sharing secondary servers of the other ccTLDs
• <specific proposal today>– Making a team to see whether such Working Group is useful or
not for ccTLDs