Theo

Question 1

Sockets

Answer 1

• endpoints of logical connections
• consist of an IP address and a port number

Question 2

Difference between TCP and UDP (+ sequence and acknowledgement numbers)

Answer 2

• Transmission Control Protocol (TCP) provides logical connections and reliability
  
  • takes care of flow control
  • Data divided into segments
  • Each data byte has a number
  • Sequence number: number of first data byte
  • Receiver confirms with sending acknowledgment number and - flag
  • resent
  • E.g. Email, FTP
• User Datagram Protocol
  
  • provides connectionless and unreliable IP service to the application layer
  • package can be sent without prior connection
  • not resent
  • E.g real time applications, such as a video/audio streams or video games

Question 3

Network Access Point or Internet Exchange Point (IXP)

Answer 3

• network node interconnecting networks of different internet service providers (ISPs)
• on layer 1 (using Ethernet)
• Border Gateway Protocol: to announce routes between participants of an IXP and makes routing decisions based on path, network policies and/or rule-sets

Question 4

Routers

Answer 4

• forward data packages between different networks
• Network layer (read IP headers)

Question 5

Gateway

Answer 5

• interconnects networks working with different protocols
• transport or even the application layer (translation between various protocols)

Question 6

Internet Backbone

Answer 6

• main data routes between large networks and routers (traffc between countries and continents)
• hosted by high-capacity network centers

Question 7

WAN

Answer 7

• Wide Area Network
• network across a large region (nation, state)

Question 8

LAN

Answer 8

• Local Area Network
• Small network (single room up to several buildings)

Question 9

Schaubild

Answer 9

Question 10

split horizon with poisoned reverse

Answer 10

• he cost is set to infinity for every node which contains “B” in the column “Next
• does not protect against all forms of loops, but under special network situations against the count-to-infinity problem

Question 11

MTU

Answer 11

• maximum transmission unit
• largest protocol data unit that the network protocol can pass onwards
• specified in bytes
• MTU = MSS + (IP & TCP) headers

Question 12

MSS

Answer 12

• largest amount of data that the network protocol can handle in a single, unfragmented piece
• specified in bytes

Question 13

ACK field

Answer 13

• maximal received sequence number (SEQ), up to which all bytes have been received correctly, plus 1
• Caution: storage of receive buffer

Question 14

packet

Answer 14

• (or package)
• data unit sent over a packet-switched network
• Depending on layer and protocol: frame, datagram, segment

Question 15

frame

Answer 15

• another name for packet on the second layer (data link layer)
• sent over a single link

Question 16

datagram

Answer 16

• independent entity of data
• sufficient information to be routed from the source to the destination computer
• packets of an unreliable service
• third layer (IP and UDP)

Question 17

segments

Answer 17

• packets exchanged on the transport layer

Question 18

Recall

Answer 18

• relevant documents retrieved/all relevant documents

Question 19

Precision

Answer 19

relevant documents retrieved/all documents retrieved

Question 20

recall - precision

Answer 20

Question 21

Native approach

Answer 21

Wenn was nicht passt, wort eine Stelle nach rechts und von neuem

Question 22

Aufgabe: 2 aggregated search engines vs. all other single ones: recall and precision

Answer 22

Question 23

IP-header Beispiele

Answer 23

Question 24

TCP

Answer 24

TCP is a host-to-host protocol for reliable communication

Question 25

Internet Protocol provides a connectionless and unreliable service for the transport layer

Answer 25

Question 26

By what factor does IPv6 increase the address space if you compare it to IPv4?

Answer 26

Question 27

objectives for the introduction of IPv6

Answer 27

increase the address space

Question 28

OSI / ISO vs. TCP/IP Model

Answer 28

layered architecture allows to exchange the protocols more easily e.g. IPv4 ↔ IPv6

Question 29

Which network components use the information in the IP headers

Answer 29

Question 30

disadvantages of IPv6 over IPv4

Answer 30

Question 31

static vs. dynamic routing

Answer 31

Question 32

Internet communication layers

Answer 32

Question 33

advantage of a packet switching network over a circuit switching network

Answer 33

Question 34

Internet vs. WWW

Answer 34

Internet is the general network WWW is one of the (high level) services

Question 35

DVR vs. Link-state-Algo

Answer 35

count-to-infinity problem

Question 36

Link-State routing steps

Answer 36

step 3: compile the Link-State packets step 4: the network is flooded with these Link-State packets stept 5: shortest path from node A to every other node using Dijkstra's algorithm

Question 37

count to infinity problem Erklärung

Answer 37

* As soon as the **link** between router C and router D **fails**, router C will **no** longer get any more distance **information** from router D * but receives from router A that it can reach router D * **routing loop**, causing all routers to increase their distances * gradually reach infinity * because just the indexed vectors with distances, but no **corresponding links** are being distributed

Question 38

(Link-state Routing) Link-State packets consist of

Answer 38

Question 39

Editing distance Levenshtein distance (a special form of the Editing distance) formale

Answer 39

Question 40

KMP Regel

Answer 40

!= oben = unten

Question 41

Bestcase BM (mh)

Answer 41

**O(n/m)** ## Footnote If the mismatch occurs at the rightmost symbol, the pattern can be moved by m positions (m stands for the number of letters in the pattern).