The deck: ports, defaults, prefixes and IOS commands
Cards run from transport ports through default values and addressing to IOS commands. Say the back aloud before you open it; a card you hesitate on goes back into tomorrow’s pass.
0000SSH and Telnet: transport and port
SSH: TCP 22, encrypted session. Telnet: TCP 23, everything in cleartext, passwords included.
0001DNS: transport and port
Port 53. Ordinary lookups use UDP; DNS also uses TCP 53.
0002DHCP: server and client ports
Server listens on UDP 67, client on UDP 68. The exchange: Discover, Offer, Request, Ack.
0003TFTP: transport and port
UDP 69.
0004NTP: transport and port
UDP 123. Lower stratum = closer to the reference clock.
0005SNMP: the two ports
UDP 161: the manager polls the agent (get, set). UDP 162: the agent sends traps and informs to the manager.
0006Syslog: transport and port
UDP 514.
0007RADIUS: ports and what it encrypts
UDP 1812 authentication, UDP 1813 accounting. Only the password is encrypted.
0008CAPWAP between a lightweight AP and its WLC
UDP 5246 control, UDP 5247 data.
0009Default administrative distance: connected, static, OSPF
0, 1, 110. AD chooses between route sources; lower is preferred.
000aDefault spanning-tree bridge priority
32768 plus the VLAN ID (extended system ID). Set it in multiples of 4096; the lowest bridge ID becomes root.
000bSTP short path costs: 10 Mb/s, 100 Mb/s, 1 Gb/s, 10 Gb/s
100, 19, 4, 2 (802.1D-1998 values).
000cRapid PVST+ port states
Discarding, learning, forwarding. Blocking and listening belong to classic 802.1D.
000dRapid PVST+ port roles
Root, designated, alternate, backup.
000eVoice VLAN and access VLAN on one switch port
The phone’s traffic is tagged in the voice VLAN; the attached PC’s traffic stays untagged in the access VLAN.
000fOSPF default reference bandwidth
100 Mb/s. Cost = reference ÷ interface bandwidth, so every link of 100 Mb/s or faster costs 1.
0010OSPF router ID: order of selection
1. Manual
router-id. 2. Highest loopback IPv4 address. 3. Highest active interface IPv4 address. A change takes effect after the OSPF process resets.0011HSRP defaults vs VRRP
HSRP: priority 100, preemption off. VRRP: preemption on by default.
0012Syslog severity levels 0 to 7, as IOS names them
0 emergencies · 1 alerts · 2 critical · 3 errors · 4 warnings · 5 notifications · 6 informational · 7 debugging. Lower number = more severe;
logging trap warningssends levels 0 to 4.0013IPv6 prefixes to recognize
Global unicast
2000::/3· unique localfc00::/7· link-localfe80::/10· multicastff00::/8. IPv6 has no broadcast.0014Modified EUI-64 interface ID from a MAC
Split the 48-bit MAC in half, insert
FFFEin the middle, invert the 7th bit of the first byte.0015Numbered IPv4 ACL ranges
Standard: 1–99 and 1300–1999. Extended: 100–199 and 2000–2699.
0016ACL keywords host and any as wildcards
host 10.1.1.1=10.1.1.1 0.0.0.0.any=0.0.0.0 255.255.255.255.0017show ip interface brief
One line per interface: IP address, OK?, method, status (layer 1) and protocol (layer 2).
0018show vlan brief
Each VLAN’s ID, name and status, with the access ports assigned to it. Trunk ports are not listed.
0019show mac address-table
Learned and static MAC addresses by VLAN, with type and the port each one sits behind.
001ashow cdp neighbors
Directly connected Cisco devices: device ID, local interface, holdtime, capability, platform and remote port ID.
001bcopy running-config startup-config
Saves the active configuration from RAM to NVRAM so it survives a reload.
001cGive a switch a management IP address
interface vlan 1, thenip address 192.0.2.10 255.255.255.0andno shutdown; in global configuration,ip default-gateway 192.0.2.1.
How the deck is laid out
The cards follow the route a packet takes through the blueprint: transport ports first, then the defaults that decide which path and which switch wins, then the address prefixes, then the commands you type to check all of it. Each group links back to its study area in the CCNA study guide when a card needs more than a one-line answer.
- Ports and transports pair with the components, cabling and TCP/UDP study area and the TCP vs UDP concept.
- Administrative distance, OSPF cost and router ID sit under routing tables and static routes and OSPF and first-hop redundancy.
- Bridge priority, path costs and port roles belong to Rapid PVST+ and EtherChannel.
- Syslog levels and the SNMP and NTP ports map to device management, NTP, SNMP and syslog.
Command prompts the cards assume
| Command | Prompt | Mode |
|---|---|---|
show ip interface brief | Switch# | Privileged EXEC |
copy running-config startup-config | Switch# | Privileged EXEC |
interface vlan 1 | Switch(config)# | Global configuration |
ip address 192.0.2.10 255.255.255.0 | Switch(config-if)# | Interface configuration |
ip default-gateway 192.0.2.1 | Switch(config)# | Global configuration |
Show commands also run from configuration mode when prefixed with do, for example do show vlan brief.
Cards are the recall layer
A deck answers “what is the value”. Study also needs “what happens next” and “what is wrong in this output”, which only scenarios and labs train. Use the cards to clear the recall load, then spend the freed time there. The CCNA study materials comparison covers the books, courses and lab platforms that carry the explanations, and the free CCNA practice test puts the same facts inside full scenarios, with every answer choice explained.