# GATE2003-27

5.6k views

Which of the following assertions is FALSE about the Internet Protocol (IP)?

1. It is possible for a computer to have multiple IP addresses
2. IP packets from the same source to the same destination can take different routes in the network
3. IP ensures that a packet is discarded if it is unable to reach its destination within a given number of hops
4. The packet source cannot set the route of an outgoing packets; the route is determined only by the routing tables in the routers on the way
0
it should be of 2 marks.

In computer networking, source routing, also called path addressing, allows a sender of a packet to partially or completely specify the route of the packet takes through the network. In contrast, in non-source routing protocols, routers in the network determine the path based on the packet's destination.

http://en.wikipedia.org/wiki/Source_routing

edited
26
Yes. You are correct. A computer can have multiple IPs as it can have multiple network interfaces.
0
@Arjun Suresh : Sir in D option if Router will not determine the route then who will determine the route. As IP is connectionless and unreliable protocol. And each packet contains source as well as destination address. So that way only Routing algorithms which make entries in Routing Table will determine the route.
27
@GATE : sometimes Source decides entire route for a packet that is Strict source routing. There is an Option Field in IP header which used to tell  is it Strict/ Loose source routing.

http://www.networksorcery.com/enp/protocol/ip/option009.htm
1

@Arjun sir is the answer wrong? Because I found following on the internet. Also if (d) is not the answer, then which one is?

Summary: Source routing is very well possible in both IPv4 and IPv6. Its just that network admins are recommended to disable it!!! But nothing like impossible to do as long as current protocol definitions go...

In the Internet Protocol, two header options are available which are rarely used: "strict source and record route" (SSRR) and "loose source and record route" (LSRR).[3] Because of security concerns, packets marked LSRR are frequently blocked on the Internet. If not blocked, LSRR can allow an attacker to spoof its address but still successfully receive response packets.[4]

In IPv6, two forms of source routing have been developed. The first approach was the Type 0 Routing header [5]. This routing header was designed to support the same use cases as the IPv4 header options. Unfortunately, several important attacks against this routing header and its utilisation was deprecated[6]. A more form of source routing is being developed within the IETF to support the IPv6 version [7] of Segment Routing .

### SOURCE BASED ROUTING, BY THE SUGGESTION OF IETF NEEDS TO BE DISABLED BY DEFAULT ON NETWORKING DEVICES. AT LEAST IT SHOULD BE AS THE FEATURE ITSELF IS RECOGNISED AS A MAJOR SECURITY THREAT AND IETF ITSELF IS TRYING TO GET RID OF IT.

next it says:

IPv4 networks are now safe because almost all network administrators listen to the suggestion of IETF and other security folks and in order to prevent security issues source routing options on routers are almost always disabled. After a while it resulted in that most vendor default configuration for devices is disabled source routing al least on router devices.

When we speak about IPv6 negative security impact regarding source routing enabled by Type 0 Routing Header is even worst than in IPv4. This resulted in IETF tries to completely deprecate the Type 0 Routing Header. It will basically means that the source routing in IPv6 protocol is completely kicked out of RFC.

0

option d is corrct

But before beginning our foray into IP, let’s take a step back and consider the
components that make up the Internet’s network layer. As shown in Figure 4.12,
the Internet’s network layer has three major components. The first component is

the IP protocol, the topic of this section. The second major component is the rout-
ing component, which determines the path a datagram follows from source to des-
tination. We mentioned earlier that routing protocols compute the forwarding

tables that are used to forward packets through the network. We’ll study the
Internet’s routing protocols in Section 4.6. The final component of the network
layer is a facility to report errors in datagrams and respond to requests for certain
network-layer information. We’ll cover the Internet’s network-layer error- and
information-reporting protocol, the Internet Control Message Protocol (ICMP), in
Section 4.4.3.

line from korose-ross

page 332

0
But at a given instant a computer would have a specific IP address right?

If the IP address changes packets would be lost.
0

@Arjun sir

I agree for D is False

But why not A?

As per my knowledge IP address should be unique for system within the network.

how a computer can have multiple IP addresses?

4
Yes, a computer can have multiple IP Addresses if it has multiple Network Interface Cards (NIC). Each NIC having a unique IP. Your computer comes with a built-in NIC and you can buy another, add it into the motherboard thus having multiple IP Addresses.
0

So, point to be noted,

multiple and unique are two different things.

multiple means more than one.

got it.

1

You can see it practically.

Connect your computer /mobile to a WiFi an search on Google as

My IP Address. Then switch to your mobile data and again search for the same.

You will see that you will be shown 2 different IP Address as your Internet service provider is different in both cases.

Hence option A is a TRUE statement.

0
But at different times. A source cannot have the same IPs at the same time. Here is not the stronger answer but definitely incomplete.
0

Option-D

1. The packet source cannot set the route of an outgoing packets; the route is determined only by the routing tables in the routers on the way
2. Bcz in strict source routing or lose source routing path is set by the source not by router and main task of router is to check outgoing path with the help of forwording table inside it.
0
Source decides entire route for a packet that is Strict source routing ... Then how is routing table helping it ??
0
source decided routes for packet that is actually SSR
1. It is possible for a computer to have multiple IP addresses   False
2. IP packets from the same source to the same destination can take different routes in the network     True
3. IP ensures that a packet is discarded if it is unable to reach its destination within a given number of hops   True
4. The packet source cannot set the route of an outgoing packets; the route is determined only by the routing tables in the routers on the way   True

Every computer has a unique IP address, So Option A will be answer as it is false.

1
A is true since a router can have multiple IP addresses for each interface.

B is true since IP is a connectionless protocol that uses the datagram approach which means that each datagram is handled independently and can follow a different route to the destination.

C is true since if there is ttl associated with each packet, which means the maximum no of hops it can have. When it becomes zero,the packet is discarded by the intermediate router and time exceeded message is sent to the source to inform it about the situation .

D is false since a source can predetermine a route for the datagram as it travels through the internet.this is done with the help of strict source routing option
A ip's are unique.

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