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Category: CCNA 200-125

CCNA 5.2: Troubleshoot client connectivity issues involving DNS

Overview: Troubleshooting client connectivity issues involving DNS typically comes down to whether or not a client can resolve a domain name to an IP address   Study Notes: Troubleshooting client connectivity issues involving DNS typically comes down to whether or not a client can resolve a domain name to an IP address What does it […]

CCNA 4.7: Describe basic QoS concepts

Overview: Quality of Service (QoS) is a way to tell routers and switches to prefer, process and prioritize some packets over others.   Study Notes: By default, QoS is not applied and packets are treated as First In First Out (FIFO) Some packets like Voice over IP and Video are time sensitive and should be […]

CCNA 4.6: Configure and verify single-homed branch connectivity using eBGP IPv4

Overview: External Border Gateway Protocol (eBGP) is when BGP is run between two different Autonomous Systems   Study Notes: BGP is a path vector protocol It makes routing decisions based on the Best Path Algorithm BGP exchanges routing information with a neighbor (peer) router BGP uses Autonomous Systems.  BGP routers in other ASs are typically […]

CCNA 4.5: Describe WAN access connectivity options

Overview: WAN access connectivity options include MPLS, Metro Ethernet, Broadband PPPoE, Internet VPN (DMVPN, site-to-site VPN, client VPN)   4.5.a MPLS Multiprotocol Label Switching directs data from one network node to the next based on short path labels rather than long network addresses avoiding complex lookups in a routing table. Multiprotocol – protocol independent transport. […]

CCNA 4.4: Describe WAN topology options

Overview: A few different types of WAN topology options exist.  The concepts behind WAN topology can apply to Layer2 or Layer3 of the OSI model.  These are the four types of WAN topology optoins covered on the CCNA exam: 4.4.a Point-to-point A point-to-point link provides a single, pre-established WAN communications path from the customer premises […]

CCNA 4.3: Configure, verify and troubleshoot GRE tunnel connectivity (FREE LAB!)

Overview Generic routing encapsulation (GRE) is a simple site-to-site VPN tunneling protocol.   Study Notes: Nonsecure, site-to-site VPN tunneling protocol Used to tunnel IP packets across the internet GRE header encapsulates an IP header and packet The IP header and packet is the letter The GRE header is the envelope GRE can encapsulate any OSI […]

CCNA 4.2: Configure, verify, and troubleshoot PPPoE client-side interfaces using local authentication

Overview Point-to-Point Protocol over Ethernet (PPPoE) is a network protocol (layer 2.5?) used to encapsulate PPP frames inside of Ethernet frames. Study Notes: PPP was prevalent in the 80s and 90s.  It was typically used to connect a home PC to a server at the ISP over a 56k modem phone line connection. Point-to-Point over […]

CCNA 4.1: Configure and verify PPP and MLPPP on WAN interfaces using local authentication

Overview: Point-to-Point Protocol (PPP) and MultiLink Point-to-Point Protocol (MLPPP) are layer 2 data-link layer communications protocols used to establish connections between two directly connected nodes.   Study Notes: Point-to-Point Protocol (PPP) is a layer 2 data-link layer communications protocol PPP is used to establish a direct connection between two nodes PPP connects two devices, typically […]

CCNA 3.14: Troubleshoot basic Layer 3 end-to-end connectivity issues

Overview: Layer 3 issues include problems at the network layer with routed protocols as well as routing protocols   Study Notes: Layer 3 network layer issues Physical and Data link layers are good Network connectivity issues Possibly cannot ping Incorrect IP or subnet mask settings No gateway configured Misconfigurations Connectivity issues Neighbor issues Topology database […]