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zanfar commented on
r/ccnaPosted byA+ Network+ Security+ CCENT
4 points · 3 hours ago

It depends.

802.1t says the aggregate port has the same cost as a single port. However, various implementations may change this. For example: in IOS, two 1 Gbps ports have a cost of 3 instead of 4.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4000/8-2glx/configuration/guide/spantree.html#wp1193674

While this is technically correct (the best kind of correct), and answers the question, it is a bad idea. Never statically allocate out of your DHCP pool, nor reserve a static IP. A reservation implies that the reservation will dictate the IP of the machine--which is not the case here. A static IP implies that the IP can be changed without other configuration steps--which will bring the two out of sync. There are also DNS considerations, but those don't normally appear in home networks.

A good DHCP server will allow you to remove addresses individually from the pool--which should be the mechanism you use if you really want this method of operation. Otherwise, and the recomended solution, is to make sure your DHCP pool does not include your entire address space, and allocate statically outside of the DHCP pool.

For example, in a /24 use a DHCP pool from 100-199. Addresses below 100 are for network equipment while above 200 are for static hosts.

12 points · 2 days ago

While I get the gist of your post, I'm not sure how you draw the line from "home owners looking for advice" to "undermine those who have made careers out of learning the trade".

I think this sub, if anything, is a bit eager to send someone to an electrician instead of providing advice. Not that this is a bad thing, but there are many posts which contain problems I believe I could accomplish safely even given my lack of training where the OP is simply told over and over "hire an electrician".

Also "looking for free advice" is a bit of a cop-out, isn't it? I guess I can't expect you to have read every post in the last 28 days since your account was created, but many of those homeowner posts (I might even say the vast majority) aren't attempts to trick you into dispensing free work. Those posts are concerned people who are presented with a system they don't understand trying to come to grips with a problem. Requests for second opinions, "how bad is this", prioritization of budgets, and opinions on the best way to approach a problem are all common.

I've yet to see a response here that promotes an unsafe practice. Sure, receptacle replacements, fan installations, and switch wiring are all common, but I've never seen anyone suggest a homeowner open up their breaker box. (I'm sure this has happened, but it's not at all common). I think this sub draws a pretty reasonable line between DIY-capable projects and professional-only.

You also have to consider non-union states and the low-quality work that can be done by otherwise professional outfits. Those of you in the trade may be able to spot a fly-by-nighter, but for a homeowner looking in the yellow pages, the distinction may not be as clear.

1 point · 2 days ago

I'm not sure about complete pilots, but Californication and Nip/Tuck are still burnt into my mind as setting the mood so perfectly and so quickly for a character.

In both cases, I immediately thought "That's f--ed up" and "This goin' be good!" at the same time.

Both shows eventually let me down, but these two first scenes were iconic.

1 point · 2 days ago

...through the same cable the power comes through...

zanfar commented on
r/ccnaPosted by
3 points · 3 days ago

what is to stop another person from assigning the same ipv6 address to a host on their network?

Nothing. you can assume that everyone uses IP space assigned to them, but there are no controls to prevent this. This is not limited to IPv6.

Would they conflict?

No. At least, not in the way I think you are thinking. The good news is that most of the Internet follows decent pracitces, and that means that their misconfiguration won't propagate. Most of the rest of the world would still point to the correct location for that IP. However, on their network, as local routes take precedence over default routes, all the traffic that should go to you will instead be send to the misconfigured machine.

2 points · 4 days ago

Honestly, those numbers are so close you're not going to see a difference.

However, in e-mag theory, the antenna gain is more important as it works both ways--the losses in a communications channel use the transmitting device's output power, but both antenna gains. Given that the host devices will likely be the lower-power devices, I would go with higher-gain antennas (if that was absolutely the only difference).

zanfar commented on
r/ccnaPosted by
3 points · 4 days ago

Depending upon the device and IOS version, send log is the command to generate a custom log message (and send it to whatever logging facilities are enabled).

6 points · 5 days ago

I swear this is the third time I've posted the below information this week:

The only accurate source as to what is, or is not, on the certification exam, is the official topic list published by Cisco. I don't care if it's in a book, if the document says "official", or if a Cisco-Certified-Whatever told you so; if it's not on the topic list, you won't be graded on it; if it is on the topic list, you should know it back to front.


ALL courses, even NetAcad, are just someone's idea of how to teach you to 1) pass the test, and/or 2) learn the topics. As such, you should expect for them to teach you things they believe are important, but that you won't get tested on, as well as for them to leave topics out that you will get tested on. Always review the topic list before taking the exam.

All that being said, no, LSAs are not a part of the CCNA as far as I know. (but you're not taking my word for it, right?)

3 points · 5 days ago

/u/CiscoJunkie is correct, most of it's use is deep, deep troubleshooting--that is, when normal troubleshooting steps have resulted in two, seemingly incompatible, conclusions.

I will add, however, that most of my Wireshark use is proving to other departments that it's not the network: either by showing the packets getting to the host (nope, no connectivity issues) or showing no packets leaving the host (I can't be dropping frames if you're not sending them).

However, the way our departments communicate is truly dysfunctional, so that may just be me.

7 points · 5 days ago
  • Beercade
  • Find a FLGS and demo a boardgame none of you have played
  • Top Golf is surprisingly fun, even for non-golfers, and can have a bit of an arcade feel. Pricey though.
  • Actively recruit other members
zanfar commented on
r/ccnaPosted by
2 points · 5 days ago

Does your DHCP server work with snooping off?

zanfar commented on
r/ccnaPosted by
3 points · 5 days ago

You usually have plenty of choices on which interface to apply an ACL.

  • Draw a diagram
  • Note each blocked flow, from source to destination

Best practice is to put a Standard ACL as close to the start of those arrows as possible, and an Extended ACL as close to the end of those arrows as possible.

zanfar commented on
r/ccnaPosted by
1 point · 5 days ago

What VLANs are Ports g0/0 and g0/1 in?

2.3k points · 5 days ago

Adding: you can almost always click-hold the back button to get back to a site you know is safe.

3 points · 5 days ago

Yes. The Boson material teaches you to be a CCNA, not to pass the CCNA test. Most Boson material is considered to be one of the most--if not the most--complete knowledge base available.

As always, your guide to what to expect on the test should always be the official Cisco exam topics.


Very losely speaking, the "government" of the Internet is mostly based on managing several databases of domain names and IP addresses. At the top, ICANN (Internet Corporation for Assigned Names and Numbers) "owns" the root of these databases, and then delegates regional authority to several RIRs (Regional Internet Registries).

Basically, to get assigned IP space in Europe, for example, you need to make a request to the European RIR (RIPE), who will assign you an address space from a larger block given to it by ICANN.

IMO, knowledge of the basic structure and the names of the five RIRs should belong to every CCNA.

1 point · 5 days ago

Honestly, if you have an attic AND a basement, conduit is overkill.

That being said, hub-and-spoke where possible, but some junction boxes will probably just make sense.

zanfar commented on
r/networkingPosted byCCNP, CCNA Sec
1 point · 6 days ago

I don't see any standard specification for that injector--not even PoE+ (which very often doesn't mean anything either)--which is usually a very bad sign. In my experience, it's also best to avoid budget equipment when dealing with PoE.

Does the controller manufacturer not supply a compatible injector?

I'd start here, and stay with a name brand, hopefully one that isn't tied to a particular device. Tripp Lite would be my go-to: name brand, experienced in power devices, and isn't making them for a specific AP or device.

2 points · 6 days ago
  1. Find which PoE standard your controller supports
  2. Buy a PoE injector that supports that standard

I bought the cheapest PoE injector on CDW

I have to ask, what made you think this was going to turn out well?

3 points · 6 days ago

As per TAC: The "official" S/N of a device is the "Chassis" S/N. For devices with replaceable or optional components, many internal or additional parts may have their own S/N, all of which are reported by sho inv.

This, of course, does not apply to chassis-based devices or line cards.

2 points · 6 days ago

Yeah, I had to read it a few times myself.

Maybe it's a controller limitation--like how some switches have 2x10G or 4x1G interfaces on the same 4 ports? I've only used QSFP+ as a P2P DAC, so I'm just guessing.

7 points · 6 days ago
  • Identify the appropriate IPv6 addressing scheme to satisfy addressing requirements in a LAN/WAN environment
  • Configure, verify, and troubleshoot IPv6 addressing
  • Configure and verify IPv6 Stateless Address Auto Configuration
  • Compare and contrast IPv6 address types
    • Global unicast
    • Unique local
    • Link local
    • Multicast
    • Modified EUI 64
    • Autoconfiguration
    • Anycast

As always, the Official Exam Topic List is the only resource you should use for what to expect on the test.

It's 4/14 topics in 1/5 sections, so 6% or so of questions.

3 points · 6 days ago

I agree, but the spec page is pretty clear--24x40G or 48x10G--maybe it's a typo? The 12Q, 40X, and 16X all support 1x40G -> 4x10G.

1 point · 6 days ago

Additionally, don't use a loop here, the interfaces field should take a list.

u/zanfar
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