Networking & Cellular
E06 IP Addressing & Routing — Study Guide
This guide covers IP Addressing & Routing as part of Networking & Cellular. Start with the vocabulary, then try to answer each question before revealing the answer. Connect these facts to a real network or cellular connection and practice the subject in the arcade when you are ready.
Acronyms first
| Term | Meaning |
|---|---|
| IHL | Internet Header Length |
| MTU | Maximum Transmission Unit |
| CIDR | Classless Inter-Domain Routing |
Key facts
Which Layer 2 limitation does the Network Layer solve with hierarchical addressing?
Flat addressing
Why isn't a single global network possible at Layer 2?
Layer 2 operates across a single physical medium
How many fields are in the IPv4 packet header (per slides)?
14
Which IPv4 field specifies IPv4 or IPv6?
Version
Max IPv4 total packet length?
65,535 bytes
Fragmentation occurs when the packet is larger than…
the Layer 2 frame allows (MTU)
Which IPv4 field increments with the number of fragments sent?
Identification
Which IPv4 field assists in reconstructing a fragmented packet?
Offset
A 3,500-byte packet over a 1,500-byte MTU: the 3rd fragment's offset and size?
Offset 3000, size 500
All fragments of the same original packet share the same Identification value.
True
Which field sets the max number of routers a packet can pass, preventing infinite loops?
Time-to-Live (TTL)
Which IPv4 field specifies the data type in the payload?
Protocol
The IPv4 header checksum detects errors in…
the header only
IPv4 uses ____ notation; IPv6 uses ____.
dotted decimal; hexadecimal
Order the basic routing process.
Host asks nearby router to forward → Router finds another router closer to destination → Repeat until router closest to destination → That router delivers directly to host
An autonomous network is…
managed by a single organization
An IPv4 address is 32 bits divided into four ____-bit octets.
8
Each IPv4 decimal value ranges from…
0 to 255
Convert 192 to 8-bit binary.
11000000
Convert 168 to 8-bit binary.
10101000
Convert 255 to 8-bit binary.
11111111
Convert 1 to 8-bit binary.
00000001
Who has registration responsibility for IP addresses?
IANA (Internet Assigned Numbers Authority)
IANA was founded in ____; ICANN in ____.
1988; 1998
How many Regional Internet Registries (RIRs) are there?
5
Which RIR has a high concentration of addresses in the US?
ARIN
Which RIR covered the Japan Softbank address in the WHOIS example?
APNIC
Total IPv4 addresses (2^32)?
~4.3 billion
About how many IPv4 addresses are unavailable for public assignment?
600 million
RIRs receive pools from IANA as 8-bit prefixes called /8 blocks. How many exist?
256
Per the slide's table, what share of IP addresses did the United States hold?
56%
Splitting larger networks into smaller interconnected networks to reduce congestion is…
Subnetting
In CIDR, each decrement of the prefix (e.g., /24 → /23) makes the network…
2× larger
To find the Network ID, you perform which operation between the IP and subnet mask?
AND
Network ID of 192.228.16.3/16?
192.228.0.0
172.25.104.72 with mask 255.255.255.0 — Network ID?
172.25.104.0
255.255.255.0 in CIDR is…
/24
255.255.0.0 in CIDR is…
/16
Usable host range of 192.168.40.0/21 spans 192.168.40.0 to…
192.168.47.255
Host 172.19.22.140 /255.255.0.0: number of usable hosts?
65,534
Host 172.19.22.140 /255.255.0.0: broadcast address?
172.19.255.255
Host 56.2.20.7 /255.255.254.0: host bits?
9
Host 56.2.20.7 /255.255.254.0: total hosts?
510
Host 56.2.20.7 /255.255.254.0: broadcast address?
56.2.21.255
Host 56.2.20.7 /255.255.254.0: last host?
56.2.21.254
WHOIS is a ____-based query/response protocol to determine origin info about IPs.
TCP
A Network ID's dotted-decimal suffix is…
0
During start-up a ____ broadcast is used; after start-up a ____ broadcast is used.
local; directed
Loopback ('this computer') address block?
127.0.0.0/8
Which is NOT a private network range?
172.32.0.0/12
Which technique shares a single public IP among many hosts?
NAT (Network Address Translation)
NAT operates at which layers?
Layer 3 and Layer 4
Which was NOT an IPv4 challenge listed?
Too-long addresses
IPv6 improvements include autoconfiguration, improved security, and modifications for…
multicast
IPv6 hexadecimal notation: ____ 16-bit blocks separated by colons.
Eight
In IPv4 a device gets one /32; in IPv6 each device gets a…
/64 block
An IPv6 address splits into a 64-bit network part and a 64-bit…
node part (extended identifier from MAC)
In IPv6 notation, a double colon (::) represents…
consecutive blocks of all zeros
Removing leading zeros in IPv6 is called…
zero compression
First routing consideration for Host A?
Is the destination local or remote?
If the destination is REMOTE, the packet is passed to…
the default gateway
Before framing to the router, Host A checks which table for the gateway's MAC?
ARP table
What does a router reference to decide where to send a packet next?
Its routing table
Which command shows a generic IPv4 route table?
netstat -rn
Which routing table assignment is manual, doesn't reflect topology changes, and isn't used often?
Static
Dynamic routing comes in distance vector and…
link-state
Which protocol configures client IP addresses automatically on a subnet?
DHCP
Which path vector protocol backs core internet routing between autonomous systems?
BGP (Border Gateway Protocol)
Which is a link-state, shortest-path-first INTERIOR gateway protocol?
OSPF (Open Shortest Path First)
BGP is an ____ gateway protocol; OSPF is an ____ gateway protocol.
external; interior
Practice this module
Continue with a Networking & Cellular game. Choose this module in games that offer module selection.