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MX Record Theories
by gb10hkzo-nanog＠yahoo.co.uk 28 May '09

28 May '09

Hello all, First, I hope this is not off-topic for NANOG, please be gentle with me as this is my first post. I would be most interested to hear NANOG theories on the variety of MX record practices out there, namely, how come there seem to be so many ways employed to achieve the same goal ? Do you have experience in more than one of these methods and which do you favour ? To illustrate my question : (1) If you query the MX records for, Hotmail or AOL you will receive 4 equal weight MX records, each of the MX records having a round-robin set of IPs. e.g. hotmail.com. 2706 IN MX 5 mx4.hotmail.com. hotmail.com. 2706 IN MX 5 mx1.hotmail.com. hotmail.com. 2706 IN MX 5 mx2.hotmail.com. hotmail.com. 2706 IN MX 5 mx3.hotmail.com. -and- mx3.hotmail.com. 1926 IN A 65.xxxxxxx mx3.hotmail.com. 1926 IN A 65.xxxxxxx mx3.hotmail.com. 1926 IN A 65.xxxxxxx etc.etc. (2) Alternatively, some people, particularly the ones that use hosted filtering, tend to have one MX record, which as multiple round robin IPs. e.g. microsoft.com. 780 IN MX 10 mail.global.frontbridge.com. -and- mail.global.frontbridge.com. 1728 IN A 65.xxxxxxx mail.global.frontbridge.com. 1728 IN A 207.xxxxxxx etc. etc. (3) And others simply have a more traditional setup using multiple MX records and only one IP per MX record with no round robin apple.com. 931 IN MX 10 mail-in14.apple.com. apple.com. 931 IN MX 20 mail-in3.apple.com. apple.com. 931 IN MX 20 eg-mail-in2.apple.com. etc.etc. So what's the big deal ? Please note I'm not asking which is "better" ... I am just curious and interested to hear your professional opinions and experiences. Personally, I favour the simple option 3, multiple MX records. Thanks y'all.

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Packet loss statistics
by Ric Messier 28 May '09

28 May '09

Is anyone aware of useful resources for packet loss over large LANs and WANs? Google turned up a nice statistics page for Qwest's network but not much else that seems useful to me. Our testing teams are trying to simulate expected network conditions and rather than go overboard, having something close to real-world parameters would be nice. Thanks! Ric

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Re: Why choose 120 volts?
by Brandon Butterworth 28 May '09

28 May '09

> > Admittedly no one I know is nuts enough to use body parts > > for "liveness testing". Depends whose parts they're using > Just to make things clear, I am NOT going to suggest you should do so, > just telling you what I think I heared. I'm waiting for Randy to suggest his competitors do so brandon

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XO fiber cut (unverified) in St. Louis, MO
by Major Hayden 28 May '09

28 May '09

I've heard an unverified report that XO may have a fiber cut somewhere in St. Louis. Has anyone heard something similar? -- Major Hayden major(a)mhtx.net

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Why choose 120 volts?
by Seth Mattinen 28 May '09

28 May '09

I have a pure curiosity question for the NANOG crowd here. If you run your facility/datacenter/cage/rack on 120 volts, why? I've been running my facility at 208 for years because I can get away with lower amperage circuits. I'm curious about the reasons for using high-amp 120 volt circuits to drive racks of equipment instead of low-amp 208 or 240 volt circuits. ~Seth

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RIPE NCC does a series of interviews about IPv6 deployment
by Alex Band 28 May '09

28 May '09

As part of our IPv6 training project, that consists of face to face training and on-line learning modules and testimonials, I am proud to announce the first in a series of interviews. Andy Davidson of NetSumo ISP Consultancy discusses the IPv6 deployment they have done for their customers and themselves: http://www.youtube.com/watch?v=QCcigLJJbvU So far, we have interviewed 22 people from the community about their experiences and are very busy editing all the video material. In the coming months, you will be able to enjoy the rest of the interviews here: http://www.youtube.com/user/RIPENCC These interviews will also be published on our e-learning page and on our IPv6 Act Now website: http://ripe.net/training/e-learning/ http://www.ipv6actnow.org/ Cheers, Alex Band RIPE NCC

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Re: Packet loss statistics
by Chris Robb 28 May '09

28 May '09

The Internet2 network publishes 10-second data for all interfaces on both its backbone network and the individual racklans in each of its cities: Backbone: http://dc-snmp.grnoc.iu.edu/i2net/ Racklans: http://dc-snmp.grnoc.iu.edu/i2net-hp/ Default graphs don't show errors. You need to create a custom graph and click the appropriate checkbox. If you want to view a large number of interfaces with their errors on a single page, you can create a Custom View that includes errors for any number of selected interfaces. -Chris On May 28, 2009, at 12:03 PM, Ric Messier wrote: > > Is anyone aware of useful resources for packet loss over large LANs > and WANs? Google turned up a nice statistics page for Qwest's > network but not much else that seems useful to me. > > Our testing teams are trying to simulate expected network conditions > and rather than go overboard, having something close to real-world > parameters would be nice. > > Thanks! > Ric > Chris Robb, Internet2 Manager of Operations O: 812.855.8604 C: 812.345.3188 **************** ESCC/Internet2 Joint Techs July 19-23, 2009 - Indianapolis, Indiana http://jointtechs.es.net/indiana2009/

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Re: Why choose 120 volts?
by joel jaeggli 28 May '09

28 May '09

If the pdu contains a surge suppressor and was designed for 120v, plugging in to 220 will cause the MOV that protects against transient over-voltage to emit smoke. The breaker or fuse is a current limiting device. Joel Pete Templin <petelists(a)templin.org> wrote: >Dave Larter wrote: >> Seems like if the c14 was connected to a 240v PDU the 5-15 would >> deliver 240v to the equipment, arc/pop tripping the breaker on the >> PDU as soon as it is connected killing power to everything on that >> PDU. Or am I missing something? > >If you plug a PDU into a service that's higher voltage than expected, >why would the PDU circuit breaker trip? That breaker is measuring >current, AFAICT, though in the end it might be measuring power. >Regardless, it isn't measuring voltage, because that isn't constant >(it's AC, after all) and is likely to drop under a short circuit, not >skyrocket like the current will. > >pt >

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Re: MX Record Theories
by gb10hkzo-nanog＠yahoo.co.uk 28 May '09

28 May '09

On Wed, 27 May 2009 09:48:39 -0400, <gb10hkzo-nanog(a)yahoo.co.uk> wrote: > Actually, I was thinking to myself yesterday that the email world is going to be awfully > fun when IPv6 sets in and we're all running mail servers with nice long AAAA records such as > fc00:836b:4917::a180:4179. > You do realize DNS queries aren't passing around addresses in ASCII? 3 additional bytes per address isn't going to break the bank. I think you might have missed the point of my post. It was a tounge in cheek reply to the poster who suggested bad things happen if the DNS message size exceeds 512 bytes. He was commenting about AOL's MX records which currently weigh in at 507 bytes. Therefore if we were to hypothesise that the world ends at 512 bytes, then companies doing things the way AOL does, but using IPv6 addresses rather than IPv4 addresses for their MX records could run into "problems". Hope that clarifies :)

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Re: Why choose 120 volts?
by Robert Bonomi 28 May '09

28 May '09

> Subject: Re: Why choose 120 volts? > Date: Thu, 28 May 2009 01:11:41 +0200 > > On 27 mei 2009, at 18:03, Peter Beckman wrote: > > > I haven't seen a PC power supply which is incapable of both 120v/ > > 60hz and > > 240v/50hz in a very long time. > > After this nice voltage discussion, what about hertz? Would it be more > efficient for us Europeans to run our stuff at 60 Hz rather than 50? I > hear that a 50 Hz grid loses 15% more due to inefficiencies than a 60 > Hz grid. Not sure if that also applies over short distances, though. _Transformer_ losses are greater at lower frequencies. And the cores have to be bigger. That is the primary reason military avionics, and other onboard gear use 400Hz AC. Note: The U.S. as recently as immediate post WW-II had some areas of 25-Hz power. Transformer based equipment that was designed to be "just adequate" for 60Hz mains was known to 'let the smoke out' when plugged in in one of those 25Hz areas.

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