# Lab 8
## Lab 8-1
**What is the IP address of your host? What is the IP address of the destination host**

:::info
- src: 192.168.1.106
- destination: 143.89.12.134

:::

## Lab 8-2
**Why is it that an ICMP packet does not have source and destination port numbers?**

:::info
Because ICMP is in network layer
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## Lab 8-3
**Examine one of the ping request packets sent by your host. What are the ICMP type and code numbers? What other fields does this ICMP packet have? How many bytes are the checksum, sequence number and identifier fields?**

:::info
- type: 8(1 byte)
- code no.:0(1 byte)
- checksum(2 bytes)
- identifier(2 bytes)
- Seq no.(2 bytes)
- data fields(variable size)
:::

## Lab 8-4
**Examine the corresponding ping reply packet. What are the ICMP type and code numbers?**

:::info
- code:0
- type:0
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**What other fields does this ICMP packet have? How many bytes are the checksum, sequence number and identifier fields?**

:::info
:::

## Lab 8-5
**What is the IP address of your host? What is the IP address of the target destination host?**

:::info
- src: 192.168.1.106
- dst: 143.89.12.134
:::

## Lab 8-6
**If ICMP sent UDP packets instead (as in Unix/Linux), would the IP protocol number still be 01 for the probe packets? If not, what would it be?**

:::info
No. If ICMP sent UDP packets instead, the IP protocol number should be 0x11, that is 17.
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## Lab 8-7
**Examine the ICMP echo packet in your screenshot. Is this different from the ICMP ping query packets in the first half of this lab? If yes, how so?**

:::info
The ICMP echo packet has the same fields as the ping query packets
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## Lab 8-8
**Examine the ICMP error packet in your screenshot. It has more fields than the ICMP echo packet. What is included in those fields?**

:::info
The ICMP error packet is not the same as the ping query packets. It contains
both the IP header and the first 8 bytes of the original ICMP packet that the
error is for.
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## Lab 8-9

**Examine the last three ICMP packets received by the source host. How are these packets different from the ICMP error packets? Why are they different?**

The last three ICMP packets are message type 0 (echo reply) rather than 11
(TTL expired). They are different because the datagrams have made it all the
way to the destination host before the TTL expired.