snmp-getnext lexicographic table traversal example:

-- if we ask for non-leaf object, we get 1st leaf object

$ snmpgetnext -v 1 localhost public ip
ip.ipForwarding.0 = forwarding(1)

-- complete example of snmpwalk of table ipNetToMediaTable in MIB-2 ip part

$ snmpwalk -v 1 localhost public ip.ipNetToMediaTable
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.193 = 1
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.198 = 1
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.202 = 1
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.231 = 1
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.234 = 1
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.235 = 1
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.255 = 1
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaPhysAddress.1.131.252.222.193 =  Hex: 00 60 5C 82 4B 1D 
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaPhysAddress.1.131.252.222.198 =  Hex: 08 00 20 76 A8 E1 
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaPhysAddress.1.131.252.222.202 =  Hex: 00 80 48 B8 C1 6F 
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaPhysAddress.1.131.252.222.231 =  Hex: 00 A0 C9 69 53 6C 
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaPhysAddress.1.131.252.222.234 =  Hex: 00 C0 F0 1B AD 6F 
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaPhysAddress.1.131.252.222.235 =  Hex: 00 A0 C9 69 53 6C 
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaPhysAddress.1.131.252.222.255 = "ÿÿÿÿÿÿ"
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaNetAddress.1.131.252.222.193 = IpAddress: 131.252.222.193
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaNetAddress.1.131.252.222.198 = IpAddress: 131.252.222.198
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaNetAddress.1.131.252.222.202 = IpAddress: 131.252.222.202
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaNetAddress.1.131.252.222.231 = IpAddress: 131.252.222.231
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaNetAddress.1.131.252.222.234 = IpAddress: 131.252.222.234
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaNetAddress.1.131.252.222.235 = IpAddress: 131.252.222.235
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaNetAddress.1.131.252.222.255 = IpAddress: 131.252.222.255
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaType.1.131.252.222.193 = other(1)
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaType.1.131.252.222.198 = other(1)
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaType.1.131.252.222.202 = other(1)
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaType.1.131.252.222.231 = other(1)
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaType.1.131.252.222.234 = other(1)
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaType.1.131.252.222.235 = other(1)
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaType.1.131.252.222.255 = other(1)

-- example of snmp-getnext walking down 1st column, then 2nd column

1. column-first walk, table to 1st column object, row 1 

$ snmpgetnext -v 1 localhost public ip.ipNetToMediaTable
result:
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.193 = 1

... still in column 1, row 2
$ snmpgetnext -v 1 localhost public ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.193  
result:
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.198 = 1

... still in column 1
$ snmpgetnext -v 1 localhost public ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.198
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.202 = 1 
... continue until near end of column ...

$ snmpgetnext -v 1 localhost public ip.ipNetToMediaTable.ipNetToMediaEntry.ipNe
tToMediaIfIndex.1.131.252.222.235
result: 
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaIfIndex.1.131.252.222.255 = 1 
... now walk to next column, row 1 again

$ snmpgetnext -v 1 localhost public ip.ipNetToMediaTable.ipNetToMediaEntry.ipNe
tToMediaIfIndex.1.131.252.222.255
ip.ipNetToMediaTable.ipNetToMediaEntry.ipNetToMediaPhysAddress.1.131.252.222.193 =  Hex: 00 60 5C 82 4B 1D  

reference: arp table dump from box in question:

# arp -a

skynet.seas.pdx.edu (131.252.222.193) at 0:60:5c:82:4b:1d
sol.cs.pdx.edu (131.252.222.198) at 8:0:20:76:a8:e1
redstar.cs.pdx.edu (131.252.222.202) at 0:80:48:b8:c1:6f
zymurgy.cs.pdx.edu (131.252.222.231) at 0:a0:c9:69:53:6c permanent
pomade.cs.pdx.edu (131.252.222.234) at 0:c0:f0:1b:ad:6f
homebrew.cs.pdx.edu (131.252.222.235) at 0:a0:c9:69:53:6c permanent published (proxy only)
? (131.252.222.255) at ff:ff:ff:ff:ff:ff permanent
