2018-03-29 16:28:29 +07:00
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**A warm welcome to DNS**
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2018-03-30 23:05:43 +07:00
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# EDNS, Dynamic Updates, TSIG, DNAME, DNS Cookies & more
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So far we've focussed on the simplest possible form of DNS that is
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interoperable with today's internet. Over the past 3 decades however, a lot
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has been added to DNS however.
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In this document, we will cover:
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* EDNS: Extra fields carried in the additional section of a DNS message,
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including arbitrary options. The main use of EDNS today is specifying a
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larger supported UDP packet size, indicating DNSSEC support and carrying
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Client Subnet information. Defined in [RFC
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2671](https://tools.ietf.org/html/rfc2671), which also specifies several
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deprecated innovations, like additional label types.
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* Dynamic Updates: Transmitting changes to zones to master servers. Mostly
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used by DHCP servers to publish names of hosts. Defined in [RFC
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2136](https://tools.ietf.org/html/rfc2136)
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* TSIG: Secret Key Transaction Authentication for DNS. Ways to sign DNS
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messages or a list of DNS messages with a secret key. Used to authenticate
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AXFR requests and to guarantee zone integrity during AXFR. Defined in
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[RFC 2845](https://tools.ietf.org/html/rfc2136).
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* EDNS Client Subnet:
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* DNAME: ...
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* DNS Cookies: ...
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Resolvers can safely ignore dynamic updates and TSIG as they are not
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applicable to caches.
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EDNS is very much an enabling technology and it can't really be regarded as
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optional anymore. It enables DNSSEC, DNS Cookies, EDNS Client Subnet as
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well as larger UDP packets.
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2018-03-29 16:28:29 +07:00
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...
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2018-03-30 20:50:32 +07:00
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