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1500 questions
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3 answers

What happens when SYN and FIN flags in TCP headers are both set to 1?

In TCP header, what happens when both SYN and FIN flags are set to 1? Or, can both even be simultaneously set to 1 ?
MAKZ
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11
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Window Size and ACK Number

Copy-pasting from my lecturer's slides: • Receiver indicates the window size is 3000 • Transfer goes ahead • Acknowledge every 3000 bytes • Receiver increases window size to 4000 • 4000 bytes will be transferred before the next acknowledgement…
Juicy
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11
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2 answers

How to trace outgoing interfaces?

The Unix command traceroute traces the IP addresses of the nodes from a source node to a destination node. Every node in between has an incoming and an outgoing interface. Executing traceroute -n dst on src will show the IP addresses of src, dst…
ceving
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11
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3 answers

OSPF over vPC on Nexus7k

I'm trying to help a friend with some Nexus issues. The topology is like this: Cat 3750 stack -> vPC -> 2x N7k -> LACP -> Fortigate firewall cluster The 3750 stack is running OSPF to both the Nexuses. The adjacencies are up. From what I have read…
Daniel Dib
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10
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2 answers

Why can't I ping from one computer to another using L3 cisco 3550 switch?

I have configured my 3550 L3 switch to redirect HTTP traffic to a significant Machine: This is my scenario ( PCs instead of Routers): This is the switch configuration: CAT3550# show running-config Building configuration... . . ! interface Vlan1 ip…
Nidal
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10
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2 answers

why TTL value 1 in IGMP

why TTL value 1 in IGMP protocol and what are the different values possible in TTL section for Multicasting. What I got from the google is that if TTL value is 1 then it won't leave the LAN, but if it won't leave the LAN how the msg will be…
dillip_beta
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10
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1 answer

If two NICs are bonded and connected to different switches how does a router decide which switch to forward the packets to?

I am trying to understand how the architecture works in case of NIC Bonding. The scenario is: There are 2 NICs on the same system. Both are bonded to support failover and load balancing. Hence the IP of the bond driver(virtual) is the IP to which…
user3007493
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10
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2 answers

ipv6 Aggregatable global unicast addresses

Studying IPv6 addressing I haven't understood IPv6 aggregable global unicast addresses, I mean on RFC 4291 there is a generic scheme: | n bits | m bits | 128-n-m bits …
abc
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10
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4 answers

IPv4 shortage is now becoming a reality - what is needed for IPv6 to work?

Today I read that Microsoft has no more IPv4 addresses for its Azure cloud. Earlier this week I read that Latin America is out of IPv4 addresses as well. These are real - not predicted - IPv4 address shortages. I remember we had IPv6 day two years…
SPRBRN
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10
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Cisco config example for Policy Based Routing

I find my self in a situation I was in not too long ago, but I can't remember how I resolved it :) The Scenario I have a Cisco IOS router with a LAN interface (fa0/0) and a WAN interface (fa0/1), and 2nd WAN interface (fa0/2). There are two LAN…
Baldrick
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10
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1 answer

Deconfigure an interface in IOS with one command

I was wondering if there is a single command to clear a single network port's configuration? (wipe switchport, portsecurity,...)
Lucas Kauffman
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10
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3 answers

Cisco: prevent vlan's of communicating with eachother on cisco router (ACL alternative)

Setup: Cisco router with multiple VLAN's configured on it. How can you prevent 2 VLAN's communicating with eachother? Normally I would do this with ACL's like this: access-list 102 deny ip 1.1.1.0 0.0.0.255 2.2.2.0 0.0.0.255 access-list 102 deny ip…
Bulki
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10
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3 answers

SRX DHCP client compatibility with HP Procurve DHCP Relay

I am trying to bootstrap the config on some Juniper SRX100s and am having some DHCP issues. Specifically, I am connecting the 0/0 port (fe-0/0/0 in the software) to my existing network, where DHCP has worked quite reliably for just about every other…
Jeff McAdams
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10
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1 answer

Authenticate ssh key via Cisco ACS (TACACS+)

I can set a router to authenticate via a ssh public-key with: ip ssh pubkey-chain username admin key-string exit exit Is it possible to do something similar with Cisco ACS, to enable a public key to be trusted for ssh across…
glallen
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10
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1 answer

How does NAT share one public IPv4 address across multiple private IPv4 addresses

I think it's a very classical question, but, thought I've have some background, I don't have enough vocabulary anymore to search and understand correctly in the Web. Let's say I have a home network with 192.168.0.1 (IP.1) and 192.168.0.2 (IP.2) and…
Nicolas Zozol
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