[arin-ppml] ARIN-prop-167 Removal of Renumbering Requirement for Small Multihomers

Jimmy Hess mysidia at gmail.com
Thu May 3 00:11:43 EDT 2012

'On 5/1/12, Jo Rhett <jrhett at netconsonance.com> wrote:
> On May 1, 2012, at 9:52 AM, William Herrin wrote:
>> First there's DNS pinning. Because of DNS pinning, web browsers won't
>> follow your new IP address when the DNS TTL runs out. In some cases,

What?  Web servers are a snap to renumber; DNS pinning is not an
issue.     Recursive DNS servers are harder to renumber,  because the
IP addresses are often configured directly by hand  on end user
systems,  which means that a  per-system cost must be incurred  if
this activity cannot be automated,  IT staff time must be consumed to
reconfigure DNS server settings on each network device,   costs are
incurred to the END user of the ISP,  and they may be  annoyed that
their ISP's  renumbering  requires that they expend  man hours to
update configurations of their equipment.

Unfortunately, the DNS RFCs don't provide a method for a  recursive
DNS server to tell the end user client system to   permanently
reconfigure the IP address of the server queried to the new one
(without end user intervention).

A standard method of renumbering is to  transition services.
Web servers get configured with both old and new IP addresses.
The DNS records are updated, and both new and old IP addresses are
valid until renumbering is completed.

DNS pinning beyond a normal DNS TTL period would be an anomaly,  and
is likely a unique issue to be addressed by the end user   (by
rebooting their equipment).

But beyond a few days, its an imaginary problem.
Note that the ARIN /24 policy allows a 12 month transition period,
which is plenty of time
to have DNS changes to a webserver hostname take effect.

Browser windows don't get left open for 3 months.    Even if the DNS
pinning _DID_ happen to be broken in some version of a major browser
in use by users;    that can be addressed by the amount of time  that
the renumbering is performed over.

It is not as if the /24 assignment policy requirement is that the ISP
complete their renumbering  within 30 days.


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