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1500 questions
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2 answers

Network Gateways vs Interfaces

When looking at the contents of a routing table section on the Wikipedia article on Routing Tables, it contains a table as an example of a routing table with two headings which have an unclear distinction to me: Gateway and Interface. I believe a…
Alex W
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6 answers

Securing OSPF with only passive interfaces

I know that to secure OSPF you should 1) use OSPF authentication, 2) use passive interface command on interfaces that do not have ospf neighbors. If I only use the passive interface command and not ospf authentication, what vulnerabilities am I…
allred
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8 answers

Does TCP open a new connection for every packet that is sent?

This might be a silly question but a me and few buddies have been discussing the potential limitations of TCP. We have an application that is going to listen for clients (think of a gateway) and route all connected clients data through a single…
user0000001
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5 answers

How to factory reset IOS-XR?

I want to factory reset IOS-XR. The router used is ASR9000 I'm used to do that easily in IOS doing config-register 0x2102, write erase followed by a reload. I search on documentation, but found no explicit information. What is the correct method…
cgasp
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15
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3 answers

MPLS vs Encrypted VPNs - traffic security?

Why do people say a lot of times that they have two connections between two offices - the main one being over MPLS and the backup one over VPN. Why not run a VPN over MPLS too? Is MPLS secure? Can no one evesdrop on the traffic?
Yon
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15
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5 answers

How to filter non-bogon prefixes received via BGP from an Internet Exchange(IXP)?

When connected to an Internet peering exchange(IXP), what is a good way to make sure that people don't send you prefixes that they shouldn't be announcing? With regards to bogons I'm aware of the Team Cymru Bogon Reference project but when it comes…
SimonJGreen
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15
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1 answer

Why should the native VLAN never be used?

Currently studying for a CCNA Security, I have been taught to never use the native VLAN for security purposes. This old discussion from Cisco forum states it very clearly: You should never use the default VLAN either because VLAN hopping is much…
WhiteWinterWolf
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15
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2 answers

Why are there 3 ranges of private IPv4 addresses?

Why are there three separate ranges of private IPv4 addresses of different sizes? Why not just reserve the largest (10.0.0.0 - 10.255.255.255) range and let people create /16 or /24 (or whatever) networks within that range if they need smaller…
Adam Sharpe
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4 answers

Finding IP Addresses for Social Network Sites

How do I find out a company like facebook's IP addresses. I am trying to block facebook at work and having some difficulties with HTTPs and URL blocking. Everytime I block a facebook IP more seem to pop up. Is there any easy way to find out all the…
pjf
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7 answers

Quality of Service based on Layer 7 traffic

How can one perform quality of service based on layer 7 traffic? How would you classify the traffic and actively monitor and respond (dynamically prioritizing traffic)? Are there any solutions which provide a kind of weather map?
Lucas Kauffman
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15
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3 answers

Will duplicated MAC address give problems, if in different VLANs?

A small company has 2 Cisco Catalyst 3550, with 24 ports each, connecting their equipaments. After some trouble, we found that two NICs had the same MAC address. After the initial reaction of blaming who bought such NICs, etc., I began to wonder: if…
woliveirajr
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5 answers

Duplicate IP Address - which one wins?

If there's a duplicate IP address, which one "wins"? First, last, flaps, neither?
Pseudocyber
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15
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3 answers

Configure Cisco ASA in Transparent mode: Layer2 DMZ w/ Vlan translation

I am in the middle of a project to migrate some existing switched ethernet dot1q trunks behind an ASA firewall... these trunks have five vlans each (numbered 51 - 55). This is a simple drawing of the original layer2 service... One of the…
Mike Pennington
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15
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5 answers

Is PoE compatible with Gigabit Ethernet?

I'm looking for specifications for Gigabit Ethernet in connection with PoE. I saw somewhere that 1000BASE-T uses all 8 lines of the twisted pair cable. If that is the case, how does it work with PoE?
Pedr0
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2 answers

Why is my Router's WAN IP different from public IP?

My Router's WAN IP is a public IP - 172.100.x.x And my public IP is - 182.x.x.x Why do I have 2 public IP's? Does this probably mean that my router is behind another router? But then what is the use of configuring 2 public IP's?
GandalfDGrey
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