CCNA Certification Study Guide

• Ctrl+Shift+6 then X - Allows you to open more than one telnet session.
• Only the Hardware addresses change when packets go through routers.
• Half duplex Ethernet - One station can only send or receive at any time.
• Ethernet Frame - 64bytes Min 1518bytes Maximum.
• ISL frames are 1522bytes long, this can be mistaken for Giants and lost. Have to use ISL NIC cards. On router interface use 'encapsulation isl 2' to use ISL frames on VLAN 2.
• FX and SX are fibre media, 100VG-AnyLAN is twisted pair copper media.
• Spanning Tree is IEEE 802.1d - created by DEC (Digital Equipment Corp).
• BPDUs are Multicast frames, sent every 2 seconds. Blocked ports still receive BDPUs.
• Forward delay - Time taken from listening to learning (approx 50 seconds)
• Default IEEE bridge priority 32,768, used to select root bridge. If these are identical then switch with lowest MAC address is used.
• ISDN Protocols - E = Telephone network standards, I = Concepts, Terminology, Q = Switching, Signalling methods.
• ISDN Reference Points - R = non-ISDN device and TA, S/T = references point between NT1 and NT2, U = NT1 and ISDN network (US only)
• TE1 = Device compatible with ISDN, TE2 = Device NOT compatible with ISDN, TA = Converts non ISDN signals to ISDN signals, NT1 = Converts 4 wires into 2 wire local loop, NT2 = Providers equipment (Switch, PBX)
• BRI - 2 * B-channel 64kbps, 1 * D-channel 16kbps (D-channel - LAPD)
• PRI (Europe, Aus) - 30 * B-channel 64kbps, 1 * D-channel 64kbps (20.48Mbps)
• PRI (EUS, Japan) - 23 * B-channel 64kbps, 1 * D-channel 64kbps (1.544Mbps)
• ISDN supports IP, IPX, Appletalk...
• ISDN can use PPP, HDLC, LAPD, each B-channel needs a SPID
• Use static routes for ISDN otherwise it will keep link open.
• MAC address 48 bits (12 Hex), IPX address 80 bits.
• Netware 3.11 (1983-) - ethernet_802.3/novell-ether (Cisco default on Ethernet networks), Netware 3.12 or later (1985-) - Ethernet_802.2/sap - includes LLC, Ethernet_II - arpa, Ethernet_SNAP - snap, Netware 4.11 - use sap, Netware 5 uses IP
• Novell RIP - Metrics = ticks and hops (15 max), 60 sec updates (tick = 55ms / 1/18 sec)
• Novell 4.11 > uses NLSP (Netware Link Service Protocol) Link State Routing
• SAP - Updates 60 Secs - 4 = Netware file server, 7 = Print server, 24 = Remote bridge server
• Ping Responses - U = unreachable, C = congestion, I = user interrupt,? = unknown packet type, & = lifetime exceeded
• Trace Responses - N = Network unreachable, !H = Not forwarded due to ACL restriction, P = Protocol unreachable, U = Port could not be reached
• Ethernet 5-4-3 rule = Between 2 nodes there can only be max 5 segments, 4 repeaters and only 3 segments must have users.
• 80/20 rule - 80% of traffic should be local 20% across backbone
• Class 1 repeater (translational) - delay 140 secs, number you can use 1
• Class 2 repeater (transparent) - delay 92 secs, number you can use 2
• CSMA/CD - Used on half duplex devices
• Auto-negotiate on FastEthernet checks link speed and duplex of line.
• Protocol field in IP header - TCP = 6, UDP = 17, ICMP = 1, IGRP = 9
• Ports - 20 FTP data, 21 FTP program, 23 - telnet, 25 - SMTP, 69 - TFTP, 53 - DNS, 80 - HTTP
• Loopback address - 127.0.0.1
• ACL - Standard ACL as close to destination as possible, Extended ACL as close to source as possible
• IP = 1-99, Ex IP = 100-199, AppleTalk = 600-699, IPX = 800-899, Ex IPX = 900-999, IPX SAP = 1000-1099
• Remember that there is an explicit ACL of 'deny all' if no statements match.
• Multiprotocol routing supports more than one routing protocol, allows a router to deliver packets from several routed protocols.
• Core Layer - High speed switching - free from filtering or anything which will slow packets etc.
• Distribution Layer - Packet manipulation, address area segregation, broadcast domains, VLANs, security (ROUTERS), WAN access, queuing, firewalls, multicast domains, ACLs
• Access Layer - End users, ACL/filters, remote access, shared bandwidth (SWITCHES), segmentation, DDR
• HSSI - 52Mbps max
• ATM cell size - 53bytes
• Cisco LMI - DLCI - 16-1007, ANSI LMI - DLCI 16-992 (DLCI = 10bits)
• LMI is a special DLCI = 1023
• LMI Multicasting reserved for 1019-1022
• LMI extensions - Virtual circuit status, multicasting, global addressing, simple flow control
• LMI types Cisco (default), ansi, q933a. From IOS 11.2 LMI is auto-sensed
• Class A - 1-126
• Class B - 128.1-191.255
• Class C 192.0.1-
• Class D - (1110 highest order bits) - remaining bits for multicasting
• Class E - (1111 highest order bits) - Reserved for future use
• RIP 1 (Classful), single subnet, periodic updates of full routing table, max hop count 15
• RIP 2 (Classless addressing), triggered updates, full routing table updates
• Directed Broadcast - All host bits set to 1 received by all hosts on local broadcast domain.
• Local Broadcast (255.255.255.255) - All bits set to 1 received by all hosts on local and remote broadcast domains.
• Synchronous serial links default to HDLC on Cisco routers
• VIP cards - type slot/port adapter/interface (e.g e/1/0/2) (remember first interface is 0 not 1)
• IGRP Metrics - Delay, Bandwidth
• Default route - ip route 0.0.0.0 0.0.0.0 172.16.20.1 - need to use 'ip classless' (Classless is enabled by default on IOS 12.x) (Only work on stub networks)
• ip default-network 172.16.1.0
• CDP timer default 90 secs, holdtime 240 secs
• Trunked links - FastEthernet or GigabitEthernet only
• Frame Tagging - ISL = Adds it's own FCS, Cisco propriety (default), IEEE 802.1q
• LAN Emulation (LANE) - Used for multiple VLANS over ATM
• 802.10 - FDDI Frame Tagging
• Hosts can only communicate between VLANS using Layer 3 devices
• VTP Modes - Server (Default for Catalyst switches) Need at least one server in a VTP domain. All changes are advertised. Client - Sends and receives updates. To make a switch a server make it a client first then promote it once it's VTP database has received the latest revision. Transparent - Does not participate in VTP domain, but forwards VTP ads through trunked links. They keep their own database.
• VTP adverts sent every 5 mins or when a change occurs, changes only kept by other switches if higher rev no than their current version.
• VTP pruning - If a switch does not have any ports configured for VLAN 5 then it won't receive updates for it. Disabled by default. Enabled across entire domain if configured. VLAN 1 is not pruning eligible.
• Config Reg - 00 Rom Monitor, 01 Boot Image from ROM, 02-F NVRAM, Bit 6 set to 1 to ignore NVRAM. Register is 16 Bits.
• 1900 Switch Config - enable password level 1 - usermode, level 15 - enable password.
• 1900 switch can have up to 64 VLANS. You cannot telnet from a switch but you can telnet into it.