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Formed with interstitial vacuities
Exhausting karate class last night -- I had a joint lesson with the new girl (a fresher called Vicky who's currently a green belt, going for purple belt in December), and it was hard work keeping up with her as we went through every wasa we'd learnt so far. Then, when we finished and Sensei asked (as he usually does) if we had any questions, she asked about the correct way to do press-ups. Large numbers of press-ups used to be a grading requirement, which is why she was worrying about it, but they're certainly not on the syllabus any more (though obviously they're still a useful thing to do for strength/fitness). Anyway, never one to leave a question unanswered, Sensei gave us (and the guys who'd arrived for their class after ours) another 15 minutes or so on press-ups and sit-ups. Just what I needed. My only consolation was that I managed to rest my dodgy knee and look hard in the process by doing Boys' Press-ups instead of Girls' Press-ups.
Not feeling very confident about the impending grading (December 13th), but then I've not yet felt confident about a grading, and I've not yet failed one. I do need to practise more, though.
I spent the rest of the evening finding out about nameservers, being cryptic about high-speed penguin exchange in email, failing to write job applications, and having a confusing telephone conversation with a random Eastern European woman. This last was because I was trying to get some sense out of HSBC, because I wanted to check my credit card statement online, so I could get the magic number for activating my PayPal account, because ... [trails off into boring house-that-Jack-built anecdotal mooing]. ANYway, I went to www.hsbc.co.uk, entered my Internet Banking number, and it popped up a new secure window... which said something like "Owing to a period of inactivity we have disconnected you from internet banking for your security." I tried reloading the page and so on in case it had cached something, but it still didn't work, and something about their wording made me worry that in fact they'd deactivated my access to Internet Banking altogether (I hadn't used it for months), so I phoned the helldesk. The girl who answered seemed a bit confused, and when I said the magic word "URL" she hastily said "I'll hand you over to our technical people".
So she did, and there followed a period of some confusion while the nice Eastern European lady (I'm going on her accent, okay? Maybe she's actually from Hull, and just talks funny) tried to talk me through the menus in IE for the PC, and I tried to explain to her that I had a Mac but if she just told me what I was looking for then I could probably find it. Anyway, she suggested clearing the cache, which I did, and which had no effect; I then asked if it was likely to be something to do with the proxy, and she started wittering about how she'd need to give me a "proxy exception", and if I was willing to use a standalone PC (I'd already tried, ill-advisedly, to explain our network situation to her by this point) then it'd all work. In the end I just had to say "Look, if you can confirm there's nothing wrong with my Internet Banking account then I can probably fix it at this end". Which I did, FSVO "fix", by bypassing the local proxy.
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sion_a later fixed it properly (we hope) by adding ".jsp" and ".jhtml" to the list of Things Not To Cache. And now I know what JHTML is. Which is nice. Well, it's nice to know. JHTML itself seems inherently evil...
It was a good evening for learning things;sion_a gave me a tutorial in the basics of How Networks Work, which was really interesting -- after I said that what I wanted was basically the TCP/IP Colouring Book he pitched it at exactly the right level & explained how our machines talk to each other. :-) He's really very good at explaining technical stuff, although I think sometimes the analogies I use when I'm trying to assimilate information confuse him a bit (probably because they only make sense IN MY HEAD). He then set me a homework assignment to go and find out "how domain names get translated into IP addresses". I'm currently reading RFC 1034 for fun. ("Fun" is a relative concept, okay?)
So anyway. I'm setting myself up for looking extremely stupid here, but: ask me more questions about networking. If I don't know the answers (as I almost certainly won't), I'll go and find out. You see, this stuff makes my brain hurt, and that reassures me that the old grey matter isn't completely dead.
Not feeling very confident about the impending grading (December 13th), but then I've not yet felt confident about a grading, and I've not yet failed one. I do need to practise more, though.
I spent the rest of the evening finding out about nameservers, being cryptic about high-speed penguin exchange in email, failing to write job applications, and having a confusing telephone conversation with a random Eastern European woman. This last was because I was trying to get some sense out of HSBC, because I wanted to check my credit card statement online, so I could get the magic number for activating my PayPal account, because ... [trails off into boring house-that-Jack-built anecdotal mooing]. ANYway, I went to www.hsbc.co.uk, entered my Internet Banking number, and it popped up a new secure window... which said something like "Owing to a period of inactivity we have disconnected you from internet banking for your security." I tried reloading the page and so on in case it had cached something, but it still didn't work, and something about their wording made me worry that in fact they'd deactivated my access to Internet Banking altogether (I hadn't used it for months), so I phoned the helldesk. The girl who answered seemed a bit confused, and when I said the magic word "URL" she hastily said "I'll hand you over to our technical people".
So she did, and there followed a period of some confusion while the nice Eastern European lady (I'm going on her accent, okay? Maybe she's actually from Hull, and just talks funny) tried to talk me through the menus in IE for the PC, and I tried to explain to her that I had a Mac but if she just told me what I was looking for then I could probably find it. Anyway, she suggested clearing the cache, which I did, and which had no effect; I then asked if it was likely to be something to do with the proxy, and she started wittering about how she'd need to give me a "proxy exception", and if I was willing to use a standalone PC (I'd already tried, ill-advisedly, to explain our network situation to her by this point) then it'd all work. In the end I just had to say "Look, if you can confirm there's nothing wrong with my Internet Banking account then I can probably fix it at this end". Which I did, FSVO "fix", by bypassing the local proxy.
sion_a later fixed it properly (we hope) by adding ".jsp" and ".jhtml" to the list of Things Not To Cache. And now I know what JHTML is. Which is nice. Well, it's nice to know. JHTML itself seems inherently evil...It was a good evening for learning things;
sion_a gave me a tutorial in the basics of How Networks Work, which was really interesting -- after I said that what I wanted was basically the TCP/IP Colouring Book he pitched it at exactly the right level & explained how our machines talk to each other. :-) He's really very good at explaining technical stuff, although I think sometimes the analogies I use when I'm trying to assimilate information confuse him a bit (probably because they only make sense IN MY HEAD). He then set me a homework assignment to go and find out "how domain names get translated into IP addresses". I'm currently reading RFC 1034 for fun. ("Fun" is a relative concept, okay?)So anyway. I'm setting myself up for looking extremely stupid here, but: ask me more questions about networking. If I don't know the answers (as I almost certainly won't), I'll go and find out. You see, this stuff makes my brain hurt, and that reassures me that the old grey matter isn't completely dead.
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[extra credit for finding the old way to determine this from ip address]
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- A (in PhD mode)
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- A
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TCP/IP Colouring Book
That's TCP/IP Illustrated ? :-)
Homework: Pick an arbitrary position on the OSI 7 layer model (http://www.leapforum.org/published/internetworkMobility/split/node12.html) and argue it loudly. Marks will be awarded for a forthright style and an ability to change your position without admitting you were wrong. Marks will be deducted for lauging at the 9 layer model (http://www.bitwrangler.com/gvi/real-osi-model.html).
OK, real helpfulness, er..., not sure what sort of thing you're looking at. Routing is probably worth a look for the sysadmin type stuff, or TCP retransmits for the low-level stuff.
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(this is fun, by the way (the asking questions that is (though routing's fun too (sort of))))
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And for extra credit, illustrate with the output of
/sbin/routeon fire.no subject
As for what JHTML is, I don't even really know myself, although I suspect the J stands for Java, which is inherently evil anyway.
No, no. . . Coloured Books is the protocol that JaNET used to use for email.*Er, except the traffic that goes via wwwcache.ox because it's something that is only accessible within the university.
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Not just email; all the JNT protocols had a coloured book. Email was the Grey Book. WAN (X.25) was Orange Book, LAN (Cambridge Ring) was Green Book, file transfer was Yellow Book, or something like that.
I forget - it was all 20 years ago, after all... although I probably still have some of them squirreled away somewhere.
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So what's the difference (asks a terminally unsporty person)?
Full press up: Support yourself on the balls of your feet and your hands.
Girly press up: Support yourself on your knees and hands. Remembering to keep your torso and legs in line, otherwise you're bending at the hips and they become pitifully easy and almost not worth doing.
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OK,
a) What's a switch, and what's a router, and describe the differences between them. (Extra points for the mangled history of the terms.)
B) What's Spanning Tree Protocol, and why is it needed?
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When a hub receives a packet, it sends it to everything that's connected to it. So it's using up unnecessary bandwidth on all the things that are just going to drop the packet anyway because it's not addressed to them. A switch, on the other hand, maintains a table of the addresses of the things that are connected to it, so it only sends packets where they're meant to go; so even if heaps of packets are being sent to one machine it doesn't clog up all the others.
Sort of. [Waves hands]
(Ask
So presumably the bandwidth issue is (at least part of) the "why they're rarely used". Why you might want to use one now... I don't know. I suppose if you wanted to broadcast stuff to everything on your network then a hub might do that better, because you'd only have to send the thing once (and it'd go to everything) rather than sending it to each individual thing. I'm totally guessing now, though.
(See, answering these questions is where I start looking really stupid...)
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....
switches recognise broadcast traffic, and send it to everything - broadcast packets are 'special' (you can find out how/why fairly easily).
put on a network managers hat, and think why you might want all network traffic going to your machine - even if it's not destined there.
[higher end switches can do this for specific ports too]
[1] further directions from here: the 'unusable' level of bandwidth on an ethernet[2] is about 70% of maximum. do you know why?
[2] thinwire (10base2), thickwire (10base5) and hubbed twisted-pair (10baseT)[3] - but we're into history now. potentially useful if you know how to recognise the various types though (run screaming for the first two - specially 2nd)
[3] can you say why it's 10base2/5? once again - arcana
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Let the term "switching hub" go around in your head for a bit. What does such a beast probably do?
Is a hub a repeater?
Why was using 192.0.0.192 a really, really, REALLY stupid idea on HPs part?
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Mean prople - persuade thjem to go to 801.11g! I got the all kit for the wireless side of my home net cheap back when I worked for Cisco.