diff --git a/content/notes/cosc-203.md b/content/notes/cosc-203.md
index 3af4038b7..00d5f3d95 100644
--- a/content/notes/cosc-203.md
+++ b/content/notes/cosc-203.md
@@ -21,7 +21,7 @@ tags:
 - [cosc203-lab16](notes/cosc203-lab16.md)
 - [cosc203-lab17](notes/cosc203-lab17.md)
 - [cosc203-lab18](notes/cosc203-lab18.md)
-- 
+- [cosc203-lab19](notes/cosc203-lab19.md)
 
 # Notes
 [dns](notes/dns.md)
diff --git a/content/notes/cosc203-lab19.md b/content/notes/cosc203-lab19.md
new file mode 100644
index 000000000..116919012
--- /dev/null
+++ b/content/notes/cosc203-lab19.md
@@ -0,0 +1,51 @@
+---
+title: "cosc203-lab19"
+aliases: 
+tags: 
+- cosc203
+- lab
+---
+
+1. DNS request protocol is UDP 
+
+![](https://i.imgur.com/dSOSdRK.png)
+
+2. The ports of the DNS queries are:
+	1. dest of query: 53 ![](https://i.imgur.com/FoAwUQV.png)
+	2. source of response: 53 ![](https://i.imgur.com/knH3W2I.png)
+
+3. There were 12 dns queries. They were all type A![](https://i.imgur.com/nFGVbI7.png) ![](https://i.imgur.com/uKkUuFG.png)
+
+4. Anwers within responses
+	1. 2 answers ![](https://i.imgur.com/plLag5j.png)
+	2. 3 ![](https://i.imgur.com/5AKS2tn.png)
+	3. 1 ![](https://i.imgur.com/srCM9oq.png)
+	4. 1 ![](https://i.imgur.com/lALFEjL.png)
+	5. 7 ![](https://i.imgur.com/OXFBaOy.png)
+	6. 6 ![](https://i.imgur.com/MHOIR2B.png)
+
+5. dns responses after nslookup on www.otago.ac.nz
+	1. ![](https://i.imgur.com/PRKiVlq.png)
+	2. ![](https://i.imgur.com/d1P36MI.png)
+	3. ![](https://i.imgur.com/drMqoQG.png)
+	4. ![](https://i.imgur.com/gprPSoO.png)
+	5. ![](https://i.imgur.com/u3Imagz.png)
+	6. ![](https://i.imgur.com/M1ZFhwF.png)
+	7. ![](https://i.imgur.com/bgVmCub.png)
+	8. ![](https://i.imgur.com/eiHDN1m.png)
+	9. ![](https://i.imgur.com/7A5aHYe.png)
+
+6. destination is 10.64.0.112. this is one of my local dns servers ![](https://i.imgur.com/lz8MBcI.png) ![](https://i.imgur.com/xIaz0vH.png)
+
+7. name servers are
+	1. ![](https://i.imgur.com/EQqLyDa.png)
+	2. ![](https://i.imgur.com/Xq4FHUr.png)
+	3. ![](https://i.imgur.com/v2gcibe.png)
+
+8. nslookup google
+	1. 7 queries
+	2. 10.64.0.112 (local dns server) and 216.239.34.10 (the address of the google ns2 nameserver)
+
+9. only one answer (two of the requests were refused and has no answer). each one contains a dns record
+10. 
+
diff --git a/content/notes/cosc203-lab20.md b/content/notes/cosc203-lab20.md
index 673efa227..bf4577e4e 100644
--- a/content/notes/cosc203-lab20.md
+++ b/content/notes/cosc203-lab20.md
@@ -2,49 +2,19 @@
 title: "cosc203-lab20"
 aliases: 
 tags: 
-- cosc203
 - lab
+- cosc203
 ---
 
-1. DNS request protocol is UDP 
+![](https://i.imgur.com/EnNd94C.png)
 
-![](https://i.imgur.com/dSOSdRK.png)
-
-2. The ports of the DNS queries are:
-	1. dest of query: 53 ![](https://i.imgur.com/FoAwUQV.png)
-	2. source of response: 53 ![](https://i.imgur.com/knH3W2I.png)
-
-3. There were 12 dns queries. They were all type A![](https://i.imgur.com/nFGVbI7.png) ![](https://i.imgur.com/uKkUuFG.png)
-
-4. Anwers within responses
-	1. 2 answers ![](https://i.imgur.com/plLag5j.png)
-	2. 3 ![](https://i.imgur.com/5AKS2tn.png)
-	3. 1 ![](https://i.imgur.com/srCM9oq.png)
-	4. 1 ![](https://i.imgur.com/lALFEjL.png)
-	5. 7 ![](https://i.imgur.com/OXFBaOy.png)
-	6. 6 ![](https://i.imgur.com/MHOIR2B.png)
-
-5. dns responses after nslookup on www.otago.ac.nz
-	1. ![](https://i.imgur.com/PRKiVlq.png)
-	2. ![](https://i.imgur.com/d1P36MI.png)
-	3. ![](https://i.imgur.com/drMqoQG.png)
-	4. ![](https://i.imgur.com/gprPSoO.png)
-	5. ![](https://i.imgur.com/u3Imagz.png)
-	6. ![](https://i.imgur.com/M1ZFhwF.png)
-	7. ![](https://i.imgur.com/bgVmCub.png)
-	8. ![](https://i.imgur.com/eiHDN1m.png)
-	9. ![](https://i.imgur.com/7A5aHYe.png)
-
-6. destination is 10.64.0.112. this is one of my local dns servers ![](https://i.imgur.com/lz8MBcI.png) ![](https://i.imgur.com/xIaz0vH.png)
-
-7. name servers are
-	1. ![](https://i.imgur.com/EQqLyDa.png)
-	2. ![](https://i.imgur.com/Xq4FHUr.png)
-	3. ![](https://i.imgur.com/v2gcibe.png)
-
-8. nslookup google
-	1. 7 queries
-	2. 10.64.0.112 (local dns server) and 216.239.34.10 (the address of the google ns2 nameserver)
-
-9. only one answer
+1. header
+	1. 4 fields
+		1. source port
+		2. dest port
+		3. length
+		4. checksum
+	2. each field is 2 bytes
+![100](https://i.imgur.com/dzMuJWY.png)
 
+2. payload is 980 bytes