Overview: A DHCP relay agent is any host that forwards DHCP packets between clients and servers. Study Notes: Relay agents are used to forward requests and replies between clients and servers when they are not on the same physical subnet. Relay agent forwarding is distinct from the normal forwarding of an IP router, where […]
Overview: The Cisco IOS DHCP Server feature is a full DHCP Server implementation that assigns and manages IP addresses from specified address pools within the router to DHCP clients. Study Notes: Clients send DHCPDISCOVER broadcast messages to locate a Cisco IOS DHCP Server The DHCP Server responds with a DHCPOFFER unicast message containing IP […]
Overview: A DNS lookup is the process by which a host queries a domain name and a DNS server returns an IP address Study Notes: There are two types of DNS lookups: Forward lookup – the host asks about a domain name and an IP address is returned Reverse lookup – the host asks […]
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 […]
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 […]
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 […]
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 […]
Overview: RIPv2 is an enhancement over RIPv1 in that RIPv2 overcomes three main limitations. RIPv2 accommodates discontiguous network designs, supernetting and VLSM. Study Notes: RIPv2 is an enhancement over RIPv1 RIPv2 is encapsulated in a UDP segment on port 520 RIPv2 can carry up to 25 ruotes RIPv2 includes a subnet mask field allowing […]
Overview: EIGRP for IPv6 functions the same as EIGRP for IPv4 only it uses IPv6 addresses and some of the commands are different. Study Notes: Configuration commands to use with EIGRP for IPv6 config t ipv6 unicast-routing ipv6 router eigrp eigrp router-id 1.1.1.1 no shutdown Ctrl+Z config t interface f0/0 ipv6 eigrp 1 Ctrl+Z […]
Overview: Enhanced Interior Gateway Routing Protocol (EIGRP) is a Cisco proprietary advanced distance vector dynamic routing protocol. Study Notes: EIGRP uses the Diffusing Update Algorithm (DUAL) Fast convergence Easy on processor Incremental updates EIGRP is an Advanced Distance vector protocol Combines the best of Distance Vector with Link State protocols, but is considered a […]